This aside, I don't see how distinguishing between the "core" audience and everyone else justifies an inability of the writers to find a way to end the series. You seem to be arguing that BioWare's brilliance lies in a complete and utter failure of artistic vision and communication skills.
No, that's not what I'm getting at, you just keep changing your argument. You said you and others won't get the DLC and are done playing ME3 - I'm saying you and casual fans may well be, but the core audience wants to play the DLC to get the real ending.
When I asked what your main objection to an ID ending is, you said it was that the ending wasn't from an ID Shepard's point of view. I agree that the current ending's attempt at logic in regards to the mass relays and Normandy is very weak and poorly written, but that is not directly a result of an ID ending, it's just poor writing. You haven't presented any clear objections to an ID ending itself.
To be clear, I'm not saying the star child, mass relay destruction, Normandy flight, etc is genius - far from it. What I like about the ending from an ID perspective is that it has messed with all of our minds in terms of questioning the logic, making us not want to accept the ending in its current state, and >50% don't recognize it as ID. Those three things make it a successful ID. If the ending made perfect sense, tied up all loose ends, and everybody understood it, everything would have been fine, but it couldn't have possibly been an ID ending. ID by it's nature would have to achieve the three things this ending did. So as a player, to digest the ending, we either must accept it as trash, or we accept it as a cleverly pulled off ID. I don't see too much grey area. I say Bioware is too good to make the first option true, and there is a lot of evidence to support the second option. The 3 options we are presented with, which tie directly back to Saren, TIM, and Shepard him or herself, as well as Shepard waking back up in the rubble on London with a high enough EMS score and the selection of the correct option are enough evidence on their own to support ID, regardless of all the other evidence.
You and others may not like the idea of an ID ending with a delay to gauge fan reaction, and that's fine. But me personally, I think it's awesome, and it will probably go down in video game history as one of the most notorious events ever.