I think that WoW Vanilla was a great game, and I think it is still a great game. I think that the market has changed, but WoW Vanilla sold millions of copies, and people really enjoyed that game, some of it is nostalgia coloring a lot of the past, but there are some aspects of the game that I really miss. A lot of the ownership over your particular player shifted to gear from build. Back in Vanilla talent points mattered, and you could have 5 different warriors that specialize in 5 different things.
Blizzard has done a lot to simplify the mechanics, but I think that has hurt the feel of the game. Almost every class now has a self-heal, a CC, an aggro wipe etc. It often feels like there are now 3 classes, Tank, DPS, Healer. And you fit into one of those three.
In Vanilla that hurt some classes, as they were less desirable, and the Alliance had a pretty hefty leg-up in raiding thanks to the Paladin’s versatility in CC and healing. The Horde had the Shaman, which was a lot less useful in raids, outside of Bloodlust (you needed one or two Shamans). But Paladins made the opening of BWL a cake-walk with their bubble. Though, bloodlust certainly helped with Vaelastrasz, the encounter was balanced with the Alliance in mind.
40 man raids were amazing, I was an officer in a guild that did MC and BWL, and it was such an accomplishment, but it also felt like herding cats, and class balance issues often left you to 2-3 people from a class per raid, which was hard. I ended up being a backup, because hunters got low priority, but I was the first player in my guild to get the epic hunter quest/bow.
I think it will be interesting to see how this develops. Vanilla servers (and progression servers) are very popular, and have pretty large populations. They are free, this will be 14.99$ a month. I don’t know how you can compete with free. I personally would want to play the Blizzard version, and would not want to be pirating a game that was being offered to buy (not the case now) and I am sure the blizzard polish will fix a lot of the botting/farming/spam issues in those private servers.
I am very excited to play this, and they can count me as a legacy WoW player who didn’t buy BfA, who will re-sub just for WoW Classic (and to tool around in the new expansion).