OP, your topic line is so broad and generalized it makes no sense at all.
Secondly, you clearly don't understand the reason for crit.
Crit doesn't make the game suddenly easy or anything--it provides a dps boost in an alternate way from others stats; an iffy one, too, since even at higher chances there's no guarantee for constant crits.
Maybe you're confused because the first big Crit Damage/Crit Chance boost you got hugely affected your dps. Well, I can tell you, after that, the gains slow down.
If you nerf crit then you either have to nerf the higher MPs or boost another stat to compensate. Nerfing MPs to accommodate a lower DPS system makes no sense, and honestly people who complain that one stat is overvalued are usually just mad because they can't afford it. That's fine if it's the case, just be honest.
Here's what I want you to do: Take your two best characters, your barb and your wiz, and continue to gear them until you can consistently beat MP10 Inferno, BUT stay true to your concept of Crit. Then, tell me how much "better" it was.