I must respectfully disagree. That chaos is a key part of the experience. It's hard enough to land a good hit, and I think blocking would undermine the core mechanics of the game.
As for a ranked mode...I guess it wouldn't hurt anything, but that aforementioned chaos means even the most skilled players can get skunked often, as well as new players being able to sweep a game.
A defensive power up item could be something to consider though.