The proble that I have is that it doesn't feel like a meaningful decision. I just find it difficult to imagine situations in which I'd be willing to become a fallen champion. Obviously, it isn't worth it for an aspiring ultra ending, but even for a regular character, I just wouldn't want to lose the blessing, the decreased food consumption, and the piety. Maybe if I saw that there was an artifact bracer and an artifact necklace inside then it would be worth it, but in the vast majority of cases, not worth it.
So, for me, these would not add any extra fun to the game. Instead they could subtract fun by taking up space where other fun things could be. If it was just taking up a random half a level, then sure, I can live with that. But if it's stopping a different type of greater vault being generated, one which I would find fun, then I consider that to be enough of a downside not to want to see this.