Seen at Minaide Hazukashii:

While reading Stripey’s post (and the comments) on rewatching My-Hime, the inevitable discussion popped up: what’s the deal with the ending? [...] The debate basically boils down to one of two sides: either the ending sucks because it’s a reset ending or it’s appropriate because it’s a reset ending. How does that make any sense? Well, it depends on genre.

I think that reset ending is never appropriate.

That’s where the problem of the ending arises. Some of these genres demand a dark ending, while some demand a happy ending. It’s hard to feel moe moe when everyone dies horrible, gruesome deaths. But then again, you’re not supposed to be feeling moe moe when people are dying horrible, gruesome deaths. Ultimately, it comes down to whether you had been watching the show all along as happy fun times which then go horribly, horribly wrong or as a peppy veneer over a dark undercurrent. Both are correct!

That's not relevant here, IMHO. The problem with the reset ending is creator's dishonesty and/or incompetence. It's the same for dark or light anime.

In any case, if Mai-Hime has a reset ending, it's just one more reason to drop it.