Ok, since ghostcrawler quit this silly idea that wow is dying due to casualisation has come up ALOT in forums and after a while of reading them i've decided to stop repeating myself and just make one thread to house a discussion regarding the 'real' reason WoW is 'dying'.
Right for starters lets count how many years old WoW is: nine.
Thats quite old for a game and to still have so many active players is amazing, yes it's had a few losses these past few expansions, but as much as people think it's not because WoW is becoming casual.
WoW is dying not because everything is 'easy' those are opinions spread by a vocal minority who seem to have this obsession with vanilla, well let me tell you this: WoW is 'easy' because YOU played it back in vanilla, it's easy because YOU chose the casual MMO over something like....everquest lets say.
World of Warcraft has ALWAYS been considered a casual game! Even in vanilla other mmo players would mock wow for its casual ways. 'Can't deal with it ? Go play WoW with all those casual babies lol' is one of the phrases i saw around the time of vanilla.
The thing is...WoW's casualness is why it's so popular and because people played it so much it became more and more apparent to blizzard that the more casual the game was the higher the subs would be, so they made burning crusade, dumbed down content somewhat, added advanced difficulties to try and entertain those who fancied themselves 'hardcore' then they did it again in WotLK, making even heroic dungeons an AoE spam and releasing an incredibly easy raid (Naxx 2.0) as the opening tier.
But despite all of this casualisation, blizzard where right, the subs climbed and climbed and even stablized for ages, only begining to fall when cataclysm was released, with its sparse content and hard dungeons, by this time the most popular characters from warcraft 3 where dead and after a year or so pause without content, people lost interest.
It hit the asian community harder, they had to wait several years for the release of WotLK, they had to put up with burning crusade and no new content for much longer than the western countries and many migrated to other mmo's and never came back.
In closing i belive WoW's hayday is long gone, but i also belive the subs would be even lower if blizzard had stuck to their vanilla model, they needed to move with the times to accomidate and aging and increasingly entitled playerbase whom have less and less time to play as they get jobs, begin families and such.
Their change from 'hardcore' to 'casual' has provided a small buffer to the sub drops, i have no doubt that it will eventually drop to below one million, but i do not belive that will happen until it's 15th birthday atleast.
You might not agree with the changes, hell you might even outright hate them and have quit over them, but WoW isn't about you; It's doing its best to survive as long as possible before it enevitably becomes obsolete.
TL;DR
WoW is dying because it's old, casualisation was and is nececery to keep the sub drops from falling lower than they would have if blizzard stuck to their vanilla model. WoW has always been casual and blizzard is simply accomodating this for new generations.