The only change I would make to thievery is to eliminate all +thievery gear.
A chest can only be looted once to proc lucky charm...but with +thievery gear your whole party can steal from a guy one after the other. It's gimmicky. Swap all the +X thievery tags with +sneak tags.
I also agree that thievery is kind of 'strongly advised'. Weapons and armor values go up 10%+ per level so you're at a very large disadvantage if you're not constantly recycling all your gear. I think the game would be a bit better if the scaling were reduced significantly.
