And then she was resurrected with her powers restored, which is precisely what she wanted. Where is the sacrifice? Anything she is giving up is only temporary.
Where it is established that Apocalypse gets any say in who receives Crucible and who doesn't? Now, that could be an interesting thing that might be explored, but I don't know if we can definitively say that is what is happening. It seems everyone can partake in Crucible if they choose to, they are obviously just not doing it all at once. it needs to be treated with respect, so that's one reason each individual gets the focus on them for their Crucible. The other practical reason is so mutants don't just casually throw their lives away to be placed in a queue, both treating their deaths without the required respect and potentially overwhelming the system.
This isn't even about death, it's about life. The powerless mutants reclaim their power not by passively waiting for a hand out, but denying victimhood for their rebirth. I don't think it matters the nature or "usefullness" or strength of their power. At least, that hasn't been made explicit so far.