That is an understandable concept. However, DAO allowed you to sacrifice your Warden at the end, and it's not really seen as a lesser ending than the ones where the Warden can survive (at least I haven't seen it being derided as a fail ending). It is in that context that I wonder how such endings can't exist side by side more often.
Its entirely up to perspective, however. There are some that feel that the happy ending of the game is the one with the Dark Ritual because nobody has to sacrifice themselves. I think this is more a reflection of how Dragon Age: Origins did a good job of making endings where none of them are really intrinsically superior to the other.
Most people I see that consider the ultimate sacrifice to be the bestest ending are the ones that don't feel that the Dark Ritual is worth the risk. While those that feel it is worth it, pick that one.
As I said upthread, I am not opposed to a happy outcome being difficult to get. If I have to go the extra mile, do more than simply play through the content, that's okay (as long as I don't have to dive into MP or purchase additional content of course)
What do you mean by "extra mile" though? I could easily manifest a reason that would work for myself, where the "extra mile" that I have to go includes sacrificing my own character, ensuring that everything works out the best for everyone involved. But that isn't satisfactory for you.
I suspect where we differ is not so much on whether or not an ending is happy (though I think there are important, personal preferences we have that are not the same), but on what it means to "go the extra mile."
If go the extra mile is simply "play all the content" then I don't think that's as interesting as it could be. If it is "do all the things a certain way" then I don't think that that is a good thing either. So what sort of things are considered acceptable for "going the extra mile" and which things are unacceptable?