I do understand that people think BfA isn't a good expansion, and the points you are making about vanilla being better is something I certainly agree on. Not the whole idea of vanilla, because I think it was slow, slower than BfA even when it comes to classes and so I can't see why it was better then. Some do, and of course we all think different. But the whole idea of delving into the game, use time to progress your character and so on is something I miss. That's why I think Legion was way better than BfA, but also WoD, MoP, Cata and WotLK because in Legion it required you to use time and effort to progress.
I do miss the old times, but for me it's The Burning Crusade. Vanilla had it's good days, and travelling, long dungeons, exploring was something I truly enjoyed. I think that TBC took away some of the very slow things with vanilla and focused more on content, even though it wasn't as much content it is in "modern" WoW. It's some nostalgia here though, so I am a little biased since I had so much fun in TBC.
BfA got problems, no doubt. I think it is too easy. Character progression that is. Azerite system is just there, it doesn't require you to do an effort to be done with it. Gear comes from too many sources, I read that the devs think so too, but hey, we'll see it when it happens right
BfA is the first expansion I have enjoyed PvP since TBC, and world PvP is something that has been an eye-opener for me. It started with changing main to Demon Hunter(hey, one flaw with vanilla, no Demon Hunters!) then it just came off on my other chars and I think it's really fun. I am a casual when it comes to PvP though, so if the systems are shit or not compared to other expansions/seasons, I can't really say. I do have fun however, and that might encourage me to do more.
And no, I played shit ton in BfA so far too :P