I think reducing the ability bloat, especially on normal but potentially on all difficulties, would go a long way.
Compare the amount of things you need to deal with on for example Kargath Bladefist (first boss of WoD) with Shriekwing (first boss of SL).
Normal mode bosses, especially the first half of a raid, should probably not have more then 1 mechanic per role (Tank/DPS/Healer)