Say I want to roleplay a character that's consumed by greed, I rob all the casino's, steal everything around me of even a fraction of value and then I hear the news of the Sierra Madre, oh how glorious it would be to get a hold of the valuables over there. So I go over there and do the story and I find the gold. Oh the glorious gold, in my haze I don't even bother to read the messages and just click on the computer to open up the door when I finally find out what happens... I'm locked in... My greed has gotten the best of me and now I die a suiting death for such a sleezebag as I am.

So I wouldn't say that you "fail" the DLC, the DLC allows to end your character a different way.
Sure you don't get an update on what happened everywhere else but do you need to?
Your character wasn't part of it, your character wasn't there to witness the aftermath.
Your character lies dead of starvation inside of a vault.

And Wipe The Slate clean allows for that sort of ending as well.
You don't "need to know" what happened to the Mojave or it's factions since everything has been killed off or forced away by the cloud.
The Kings, Novac, Legion, NCR, all had the same faith, dead or evacuated it.

So I would not say that either of these new endings are "failing Dead Money", they're a different approach to an ending.

NUMEROUS endings for victory pending on how you answer (Speech) to the Gen at the end. Pending on some of your responses to the Gen then to the Yes Man, you have the ability to finish the game with Yes Man army still at your disposal without them turning against you.