If anyone reactivates now and expects the WoW from yesteryear they are likely to be disappointed and will most likely cancel shortly after. That's not to say the game is bad though (or anywhere close it), it has just evolved over the years; better in some ways, and worse in others, although both of these points are arguable. I've played since vanilla beta (although I took a break through Pandaria) and I've always liked the game to varying degrees throughout its history.
The best and most fun part of this game is finding a bunch of like-minded people and doing the game with them. I've found really it doesn't matter what I do in the game, whether it's just questing, or PvP, raiding, achievements, mount grinding, etc., as long as I'm doing it with people I like then it's always fun. I'm playing these days in a great guild with some awesome people and I'm having a great time. It's not as doom-and-gloom where "nobody talks" as people make it out to be, but it is worse than it used to be as you were forced to interact more back in vanilla.
Also, people often over-hype vanilla a lot with lots of rose-tinted goggles. That iteration of the game had so many problems and quality-of-life atrocities that people seem to forget while wading into the fact that the community and 'player' feel of the game was better back then. Not that I'm disagreeing with them, I just think that right now (and over the years) the game has improved drastically in a lot of areas, and went a bit backwards in others.