I was talking with people on forums about this a while ago, and how visual clutter got out of hand on the last couple xpacs along with noise pollution, which makes for a very poor experience for melee players in particular. I'm very happy with these changes, and I truly hope they also extend it to combat sound effects so my ears won't bleed any time I turn the sounds on from all the chings, clings and battle shouts.
I play exclusively with a PS4 controller. I do WQs, Dungeons, Raids, everything on a controller. I tank on a controller. I heal on one. I DPS on one. I have zero issues and honestly perform better than when I used a KB/M. I've been a daily player since Wrath, and when my carpal tunnel got too bad I thought my WoW days were over. Thankfully, a fantastic addon enabled me to continue playing. It does take some time to get used to (about a month) but like I said, I now play better than I ever did, which surprised me. I play right at my computer, so if I need to type, I can just put the controller down and do that. It works.