In the recent patch, the fling was patched. There are many things wrong about this.

Not many players did the fling, first of all. It seems that under 1% did the fling, so it didn't cause too much of a problem.
Not much players even complained about it, but look at it now; tens of topics in just this forum of backlash of the fling being removed. And that's not even the full playerbase.
I do think the item throw was overpowered and should have been removed, but the self-fling? It's not that bad.
Along with this, it's a game to have fun, and so many fun glitches have been removed. The bridge glitch, the boomerang glitch, the glitch where spinach effect and pawers effect carries on to the podium, and maybe more I don't know about! Different people have different ways to have fun. The casual players? It's not like the fling kills them instantly or anything, and if they're casual, they probably wouldn't care too much if someone had an advantage. These people had no problem with the fling, it did nothing bad to them! The people who are more skilled and try to win? It's their way of having fun, and you've killed it.
Most casual players wouldn't want to do the fling or care about it, yet the dedicated players are the only ones who might, and they've now taken a direct blow.
There are several ways to solve this. You could return it back to the state it was before, and the casual players would be ok; they wouldn't be affected much. The more dedicated players would be happy; the fling would be back.
Another way is that along with bringing the fling back, you could so something else that improves the game beyond this topic, improving matchmaking.
Right now, matchmaking is really horrible. I, a player who does their best, frequently gets matched with players that are low level, and are quickly destroyed. Losing one game with some level 100s seems to bring me straight to a few level 15s in the next game. A single loss. Everyone wins if it's improved: casual players don't get destroyed fast sometimes, and the dedicated players get to have challenges. This would fix the fling problem, and more. (This is about quickmatch matchmaking.)
I've seen @GrannyMax mention in the post a few hours before the patch about "macro techniques," which include the fling, right? This is not macro at all! It can be easily done.
Another option could be to bring back the fling, and make it a feature of the game. You could make some 2-button combo or the same punch, jump, kick, with more time allowed between the buttons, make it a new part of the tutorial, and make it announced in the in-game news. This could probably excite some players who want to do the fling, but struggle with it, or players who don't even know about it at all, could be excited about a new move they can do.
The current solution also doesn't work well because it completely stops doing some actions while doing one. This makes several things that aren't a problem weird, such as spamming buttons when being grabbed but awake.

There are a few cases where it's actually overpowered, all of which have easy ways to fix.
In the last stages of Conveyer, the fling does get pretty overpowered, unless everyone remaining can fling. This even makes a strategy where you can try to avoid fighting and just survive to the end, which is pretty mean. Here, some things you can do is making it so that the fling is disabled in the final stages of conveyer, or conveyer entirely.
In wind tunnel you can't dropkick back onto the platform anymore, and need to climb... Except the flingers. You can just make the platform higher to stop that, and maybe make the sides have a slope or something similar.
In Typhoon, you can fling straight back from the back fin to the main area in the final stages before the fin has gone underwater. Here, you need to angle it really well, and it seems just funny. If you really want to patch this strategy, you can just make the fin lower so it sinks before this strategy can be any use, but that removes the idea of grabbing the fin at the end. Here, you can just make the fin farther away from the main body, so you can't fling straight there.

TLDR; of these non-macro techniques, the item launch getting patched is the right way for that one. But the self-fling shouldn't have been. If you want to fix this unbalanced move, improve matchmaking, (which should be done anyways,) make it a normal move public for everyone to see. This doesn't really need to be patched anyways, it's a game to have fun. Different people have different ways of having fun, some just goofing around, and some doing their best. Your most dedicated players, may of which do the fling, have taken a bit blow.

I know many people here will call me a "cheater," "retard," or other rude things, but I'm posting this, go ahead and post such things if you want though.

PiggyHead Unironic you said that, with what my final paragraph was in the post.
I'm not supporting "cheating" here, that's not my intention.
The problem is that many players are unhappy about this, and some even have quit the game.

Casual players, who play casual because it's their way of fun, don't care about winning and therefore wouldn't have a problem with this.
People who do their best, but don't care about winning, playing that way because it's their way of fun, shouldn't be affected too much either, because if they do the fling, and others do, they obviously shouldn't have a problem. If they don't do the fling themselves, they will be doing their best, and it is likely if someone is doing the fling, they will be targeted more.
Why do you have a problem with it? It getting removed is a loss for some, along with neutral for others.

    AK1 I don't like the fling because it means people can get to places before others, which can be a detriment in Lollipop Factory, and I kept accidentally flinging myself out the map.

      Cartrimino

      Well the fling can be a risky move. So it is really up to you if you use it or not.

      But I can see why the fling is being removed even tho I don't share the same opinion. You should not remove such a beloved movement tech if it doesn't break the game completely. Instead make it more accessible for everyone and nerf it. Removal is always a bad move.

      But the worst part of this is. That everyone got their movement restricted. Even if you don't know what flinging is. Heavy Punching and Junping is such a basic thing to do and that should not be removed. Even if you don't "Superman Punch". Being able to make a quick decision and jump instead of committing to the punch should be an option.

        Einsamer_Keks note the word 'accidentally'. I would be in gator valley fighting a bunch of sweats, and suddenly I would be behind the bridge with a wave about to crash in. It isn't beloved at all, it's a cheat that gives people an unfair advantage. I know I keep repeating that point, but it's true. If removal is always a bad move, do you mean that all bugs must remain in the game? No matter which way you put it, using abuse of physics to access an unintended feature and gain a legendary ahead of everyone else is cheating. Removing it was for good and there's nothing you can do about it now.

          Cartrimino I can state my opinion and that is what I did.

          Saying you can't do anything about it is really unnecessary.

          Anyway. It does seem like a beloved mechanic if you look at the backslash this patch has gotten. Never seen this community more active. But alright. Of course not everybody likes it and that is completely okay.

          If bugs hurt the game. They should be removed fast. But often times these "bugs" turn out to be quite cool and accepted as features. It Is a common thing in video games. Players will find new ways to play the game all the time. I mean that is not the best comparison because it isn't a online game but for example in devil may cry you can keep enemies airborne if you attack them quick enough. That was initially a bug but so cool it was turned into a feature.

          The fling has been around for too long. They should have removed it earlier If it was so gamebreaking.

          Now in my opinion the best way of action would be to nerf the fling and more important the item fling (which is much more problematic imo) and make it easier so it is accessible for everyone.

          But honestly what bothers me the most is that I can't heavy punch and jump. I can live without the fling but for me this update made the game feel really clunky.