Some of it is not Nea, but that the player is forced into two choices, love or death. Not death of the player character, either, but the death of Nea. The choice is basically go all the way or be a contributing factor in Nea's suicide, which some people, myself included, cannot stand. It makes us feel responsible for Nea's death, as if Luxee is guilt tripping us for not wanting to be more than friends.
Honestly, even as a long time fan, if not wanting to support this love or death choice pisses Luxee off, so be it.
Oh no, Nea would be fine as a central figure, actually, I think Nea fits that role quite well. The problem is definitely as you said, we are forced into a, literal in universe, life or death decision all for just wanting to keep it on friendly terms so we can still get the other girls and have Nea around as well without the romance, and worse, after it was said we would get a friendship option with no mention Nea would die as a result. Quite frankly, I have been holding back by quite a bit. The way I see it, this was false advertising, we were told one thing and were given another. We were told we would get friendship, but what we got was Nea's death.