I must admit.
WoW at some points really getting looklike an Asian MMO, where is more casuals than hardcore players. Damn i remember old days, when you go to Molten Core or Blackwing Lair and for hours, do an raid with 40 people! But casualization is started with TBC, because not many mention it, but 10 man and 25 raids? Fun fact is, that until WoD that's is not changed, only improved by adding hero raids like Trial of The Crusader or Icecrown Citadel.
At least, in WoD Mythic difficulty is really an challenge, i saw recently some stream where poland guild wanted to beat Blackhand on Mythic, and wipe after wipe was happend. To be honest, i not sure but for 95% next expansion will be focused on Azshara and N'Zoth.
Btw. Which WoW characters, you may like see guys in Heroes Of The Storm? Blizzard recently added Kael'Thas there.