Have to remember we have no addons as of yet, and WoW designs all their fights around the assumption that everyone runs certain addons.
I would disagree with that, WoW uses the same visual and audio clues that SWTOR does. addons get used by everyone but they are primarily designed for people who cannot adjust to those visual clues. In progression raiding most of your "crutch" addons like DBM are useless because of changes that have occurred since the PTR, timers will be off, it won't pick up on certain abilities.
The people that are relying on addons to defeat encounters are the same people who have already watched a strategy video before they even go into a fight.
WoW designs difficult fights because bleeding edge progression raiders enjoy the difficulty, Yes they have addon's running because they can but if you think they are relying on them I would disagree.
They know their characters inside and out, they can run through their rotations for all situations without watching the timers. They know the fight inside and out because they have done 50+ attempts, they know what abilities are coming, and when they are coming just from sheer muscle memory.