I've noticed this as well, but on mobs. All the mobs that I would imagine have a small shadow resistance (Shadowhide Gnolls in Redridge, for example, or the Spectral Marines and Spectral Soldiers in Wetlands) resist my shadow abilities constantly. I'm talking like 3-5 resists for every spell I cast for a mob 1 or 2 levels below me.
I'm all for mobs having the Blizzlike resists and all that, but clearly something's wrong here in the translation of actual resist stats to the % chance of that mob/player to resist spells of that element. It's one of the only things I've noticed so far that is clearly wrong, but hopefully the devs see this and fix it.