A Blizzard designer said it sometime ago: killing players is not exactly hard, is letting them win with the illusion that it was "so hard" that is more difficult. Everyone could tailor their game to the most hardcore poopsockers in the world, it just doesn't work.
MMOs have always been (traditionally) more about the loot roulette than the kill by itself, because aside from the "mythic audience", very few give a fuck about raiding the same boss 250-300 times before getting a kill, numbers, again, out of my ass, I'm sure it's a lot of attempts on average to kill a mythic boss and a fuckton to kill the hardest one. Most players are content with killing stuff in one difficulty mode, which reflects the people they are surrounded with, from soloers in LFR to the MiniVan Rerolled crowd that goes mainly for heroic, to my last iper-casual guild that was happy with normal mode.
For me these games are fun because there are other people to interact with and because content is made to last more than one trip, also I like tab targeting, levelling, often the class design, etc. but the most funny shit in MMOs is the presence of other human beings, from jackasses, to funny guys, to attention whores, to loot bitches, to superheroes, to good guy Gregs and so on and so forth. I can play a male or a female, a pedorace or a furry race just because I like their models, not because it reflects my personality (in which case I'd be 100% pedo-gay-pointy ears-with some fur, batshit crazy and maybe I am and I don't know).
WoW is probably the best game I've ever played from many points of view, but I didn't like much WoD. Considering that I loved MoP in almost every aspect (I'm heavily biased for martial arts and oriental stuff in general, that had something to do with it), I was surprised to say the least. Initially it was great, lot of fun, lot of people came back to play and Winter Holidays were an orgasm of funny Teamspeak sessions. Then we got Highmaul and then Blackrock. Sometimes inbetween all returning players disappeared, half the usual players vanished too, in the end I followed and to be honest I should have been gone at least one month earlier than I did.
I may jump in for the pre xpack patch sometimes next year, who knows? So far FFXIV is keeping me hooked well enough.