In the first place people aren't interested in how it works "anywhere", in fact they play Warcraft primarily to escape "anywhere" (i.e the real world). To expect them to also have to come home and find out their escape is now another job is pretty lame way to spend 15 bucks a month. Secondly nobody is actually providing less effort. The guy who can only play 2 hours a week is providing a tremendous amount of effort FOR HIM. Once again that's relative to. However he gets the SHAFT this expansion because some of you can play for so much longer and put in so much more "effort". Finally less effort ought to reward more than it currently does even if it doesn't reward everything it ought to give out alot more.
No they don't unsubscribe after one month because for many of those casual players one month isn't enough to get any real progress anyway it certainly wasn't in cataclysm but definitely isn't in mists. In fact it's so bad now that you get far less for your time invested then you did since basically tbc. For a casual player the time you can spend in game is worth alot less then it was in Cataclysm. The people who don unsubscribe are basically the people who play 20+ hours anyway and those folks well you can't keep them. The game cannot be sustained on their backs and you can't sate their playstyle anyway. The developers tried this expansion and well people still unsub around patches.
The 4 difficulties argument is a different story altogether. It's another facet of this incredibly poor design. The poor design that leaves NO alternative (for casual or hardcore) player that isn't raiding. For hardcores this is piss poor because well I mean your gonna do the raid on normal, having to do the EXACT SAME RAID as catch up is fucking terrible. For casuals well raiding as a whole even lfr is just terrible. Basically it's an economic concern that has been forced upon the player base. In cataclysm people were foresaking raiding and even the world so that just can't happen. People just have to be FORCED to get the most use out of the content the fun behind it not mattering one bit.
The name and the genre are meaningless in so far as people playing by and large are concerned. They are not consciously aware of the fact that they are playing an mmo when they are playing it nor when they buy it. I know of almost no one who picks up the box and instead of looking at the cool dragon or elf or whatever looks ferociously for the genre and says oh good mmo phew for a second I was worried one of the Os was missing. The name is meaningless in the same way you think the word NORMAL is just a perception. It's simple a convention that can be ignored.
I'm glad you get good ques. That's not a universal situation by any means not does it mean the runs will necesarilly go fast or be rewarding. The experience is probably the opposite. Lots of time spent for little gain, the exact opposite of cataclysm and very uncasual friendly. Very un player friendly really.