Classic raiding was raiding in its infancy and today's raids are far harder, but raiding is not the entire game. World content, elite mobs, and even normal mobs can kill you making world content much harder and more enjoyable in my opinion.
I love raiding on live and it is far harder than older content (for the mos part). However there is nothing that can kill my rogue in the open world (minus the world bosses, but those are raids). I can't remember the last time I died. I can pull countless mobs and drop them in seconds. There is no quest mob, elite or otherwise, that can hurt me. The gold world quest mobs in Nazjatar are the "hardest" and they still fall over pretty quick with a couple cds.
So, yes Classic raids and dungeon bosses are cake, but trash and world mobs are much tougher relative to our characters.