I honestly think it isn't about epics or prestige for many of the people who are only now able to endgame raid thanks to the lowered entry bar in Wrath.

I know that for me, at least, I never got to finish what I started in TBC. I never got to see the end of the story. So for me, I just want to see what's there. I want to experience the fights and see the content. I want to hear the dialogue and see what screen-filling spectacles and lore convolutions Blizz has worked up this time. Sure, I'll get some nice gear too - but that's not WHY I raid. I'll probably never see a 25-man, which means that I'll never see the best gear in the game. I'm OK with that.

Choosing to run a heroic raid over a non-heroic one provides better loot. I've heard, anecdotally, that leaving more drakes up in the Sartharion fight gives better loot. If gear is really the concern of harder-core raiders who feel disenfranchised, then it seems to me that the real issue here is that Blizz needs to provide even more recognition of doing these tasks with handicaps turned on, (Amani bear mount, anyone?) not that the concept of letting more casual players complete the instance is flawed. Right now, Blizz is mostly offering prestige (in the form of Achievements and titles) instead of gear, and maybe that's not enough incentive.

I don't think the majority of new raiders would mind if there were more recognition going to those doing the hard things, so long as they get to keep seeing all the content they paid for. Sure, some will bitch - as you say, some will just see that as the "real endgame." (In my mind, that IS the "real endgame" even today, regardless of rewards.) Some people are always going to have an entitlement attitude, wanting everything for no effort - but that's a problem with their attitude, not the game. And again, I don't think such people make up the lion's share of new raiders.