It would appear that now mob spells are unresistable. Root has a pretty craptastic resist check and most mobs cast it, and I think this is the reason why it seems like everyones getting rooted now. I'm sure it's just a bug
I have also noticed this. According to #mystats I have 620+ resist on all except Curse? And I got rooted very often by a gray mob in Sebilis. Which is out right silly.
I think Warlgor's right. It seems like every low lvl NPC spell lands on my toons. Avoid root/blind/fear/stun/charm mobs like the plague until it's fixed =P
**Edit** I do see resisted spells cast by high level mobs (Plane of Fear, for instance).