Because here, the single main heroine is a terrible menace? True, Kamidori did have the pink menace, but she was one out of three.Interesting... Nostalgia goggles? Is not that different from kamidori. I can't see why someone who like one would hate the other.
Also, the plot (and or character actions) here is egregiously, offensively dumb, to the point I couldn't get past the halfway mark or something like it. Admittedly, Kamidori's isn't stellar either, but still. Kamidori's plots work.
Furthermore, Kamidori had more interesting game systems. Take the armor crafting. In that regard as well, this game made a step back.
Add a few more points probably which I've forgotten since I played this a few years ago.
So despite superficial similarities, I prefer Kamidori over this. A lot. To the point this game's successor is the only Eushully game in years I haven't even tried (though many of their recent games have been... pretty bad, so it was coming).