I don't mind critical hits in the game as players get hit by criticals just as often as they critically hit. What I think may ruin the game though is in December when about everyone will get pets with a dragon blade on it, and I am not yet sure how the sea dragon pet will affect the game.
The reason why is because pvp will be more luck, not wisdom or skill or smarts, other then that when you fight bosses they always get critical hits and when you finally get one they block it so it's just an unfair advantage for them.
the worst part about a critial hit is when the mobs and bosses start off with anywhere from 6 - 8 pips each and they each hit you with a 6 pip spell and and each gets a critial hit/boost to go with it, you can be a dead wizard before you even get to cast one spell. granted its random but still i'd like to be able to at least get one hit in before i die.