People not wanting to lose their investment is a huge reason mmo's keep going like the energizer bunny. WoW has millions of people invested in their toons. It takes a serious fuck up to lose those players. BFA is definitely that fuck up.
Will be interesting to see what they do to get those players back, or if they even can. They better hurry. Once players leave an old mmo and start really checking out the new games, going back get's less and less attractive.
WoW still has at least a couple million active accounts though, probably more. That's a ton of income. They may just focus on keeping them and stop the bleeding.
Might be that I'm old and honestly a bit tired of this hamster wheels called MMOs, but I enjoyed WoW until Legion, because I valued mostly gameplay and that adventure feeling that some places like Suramar managed to deliver in a very convincing way (for me, at least). The fact is, thanks to constant pruning, class design is a vagon of cow shit, it has hit the lowest point of all times, I believe a monkey flinging poo on a keyboard, could have typed a better design doc than the current one. This means, that if you play a shitty character (all classes, all specs, pretty much), the rest of the game is already less enjoyable, but BfA was just crap all around: uninteresting story, bland zones (Stormsong valley is possibly the worst zone ever, but I must be exaggerating), mediocre dungeons (although Siege of Boralus was cool the first time), etc. etc.
Deciding to quit was... effortless.
For the fist time since WoW exists, I have no desire to play it *at all*, I'm disgusted, period. It would take such a rollback, that it would be similar to a NGE from SWG of old. Giving back abilities, gameplay choices, removing random loot, warforge and titanforge, goddammit, it would mean redesign this game backwards. That open letter to Blizzard? Amazing.