That said, it used to be insane button bloat for everyone. Very complex rotations. Around Legion they started reworking it. Now most specs are reduced to rotations being 3-5 buttons. Work in the occasional cool down or defensive and things just fall over. This works out very well for the casual player. Controller support was added a few expansions ago. With the most recent expansion it's reached good refinement. Some class/spec combos are easier than others.

An addon called Console Port makes it so easy to play with a controller. For leveling or daily quests, it's perfectly acceptable. I've tried it and find it quite enjoyable. I particularly like it on my demon hunter. Though don't expect to jump into competitive content. You need access to way more than a controller can provide. It slows you down.