They are bleeding subs because WoD was a pile of shit, filled with shit and with some shit on top. I have been subscribed for the vast majority of WoW life, went in during open beta and aside from short periods were life was asking my undevoted attention, I was subbed and having fun.
WoD destroyed this and I canceled in 2 months and a half (I lasted as long as I could): first an idiotic ability pruning where they completely gutted some specs, removed those useful skills that had not a slice of importance in the raid scheme, but became extremely annoying to play without; a couple examples? Removing renew from shadow priests, pet heals from destruction warlocks, fan of knives from 2 rogue specs, overpower from warriors, almost every weapon strike (but one) from blood DKs, Clash from Brewmasters, Druids being raped (but that's a few xpacks it's happening) and having lost any hybrid feeling, all of these and many more must be coupled with idiotic nerfs, such as monk Crackling Jade Lightning going from usable to shitstained shit puddle, etc.
Meanwhile arms warrior have exactly 3 buttons to use and must use Whirlwind as a filler (oh nostalgia), while they watch Rend ticks generating rage for them. You can throw your keyboard around the room and do good dps as long as it lands on its keys.
During this unmitigated disaster, everyone was playing facebook games inside a garrison, personal instance nobody ever left unless they were forced. Minigames that required only a bit of time, since ui mods actually played them and their difficulty was not falling asleep while watching them run their course. Also these minigames brought you raid gear ONE TIER ABOVE what you were raiding, which to me sounds like a fucking joke.
Orcs everywhere was incredibly annoying too.