It can be annoying on certai classes -like losing part of your fire-blizzard rotation as BLM, but i still prefer the effect it has on the gameplay over -for example- the timewalker dungeons where you are going into BC dungeons with spells intended for lvl.100 content so even at level its damn near soloable for classes like warlocks or death knights.
Its not a perfect system, but it once again makes level part of the 'difficulty' of content rather than a number you completely ignore after hitting max level.