Yep crit DMG is so good. It's the biggest part of an end game build and in almost every build PvE wise. 350% crit allows for your crit to deal ×3.5 more DMG than normal . Well actually it's 400% if you count the actual internal 50% base crit DMG you don't see.
Then if we found deadly strike , it becomes 700% the normal DMG. Brutal makes it 1050% the normal DMG.
Poison build , Frozen build and any build makes great use of the 45% crit chance to deal 350% or more DMG than normal and combined with Weaken 100%+ and many other affixes and you can see why it's so good
Good for end game floor build, farming, exp farm, etc.
Although PvP it's not a must have but it is still powerful but in PvE, it's just something you couldn't ignore.