Most modern MMO's fail because they spend too much time copying WoW. Every company wants to suck on that monthly subscription tit. MMO's don't fail because of casual or hardware content, but because they have too many similarities to WoW. At some point you have to ask, why play a WoW clone when you could play WoW? It's gotten to the point that MMO's in general need to be rebuilt, and companies need to stop looking at WoW for inspiration. Cause WoW's design is terrible in general, which is why anyone who copies it gets a terrible game. The only reason why WoW does so well is that it lives off it's name. People remember Vanilla, TBC, and WOTLK, which are totally different games compared to modern WoW.
Though yes, casualizing games would ruin them. In many ways things like grinding and killing mobs are very casual like in MMO's, which is getting boring. Let me know when Wildstar has LFR in it and that's when the game will be for sale for $1.