CM / SNS wizard builds rely on breakpoints and very clear gearing goals in order for each skill to feed itself (much like infinite mana combos in MTG). In ROS, assuming there's new gear with higher crit chance and attack speed means that the breakpoint is much more easily attained.
Now, I'm all for freeing up equipment slots and allowing there to be such thing as "too much attack speed," but my concern is that the current playstyle for the CM wizard (the most attainable way to do MP10) makes it so that the enemies aren't fighting back, and I don't see that changing in ROS. There's no accuracy for spells and your chain casts are entirely independent of any monster defenses or stats.
In DIablo 2, I was upset when they added immunities to the expansion because it ruined my Ice Sorceress (it was totally necessary, but it still stung). My thought is that this is the path for D3 Expansion ("Frozen Mod elites cannot be frozen" for example), and it will be very frustrating for people who geared for a specific playstyle.
What do you guys think?