1. Caster +damage, like with Frozen Wrath, comes at the expense of ALL OTHER STATS. Unlike you guys, casters have to rely on mana. Greens with +spell damage are garbage. You have to build up a massive set of MC level gear; eg 8-10 or so pieces of gear before you start seeing changes.
2. It's not a direct addition. Only spells that take more than 3 or 3.5 seconds to cast (or so) get the full effect from the +damage. Frostbolts do not get the full effect. If I got a full suit of all BWL gear and Warlord's gear, my 1.5 second cast Mindblast would hit for about.. 200 damage more? For a FULL set of endgame, "godly" gear. So instead of 500 it would hit for 700. Of course, I would also lose spirit, mana per 5 seconds, maximum mana, resistances, healing power, etc if I took this set of gear. Wow, uber. Sorry, but casters take it UP THE ASS in terms of itemization. Rogues have it easiest of any class.
Rogues are easy mode, keeping agro down is simple, even more simple if you're a sword rogue.
Caster have it way worse then we do, I'd like to add that the mage MC set doesn't add much damage, but mostly mana, it's a huge give and take. Where as Nightslayer, pours tons of Agility, and some strength giving the rogue more crit, AP, and dodge. It buffs all out main needs with out much choice.
So, I agree.