I can only assume that the writers and actors are big fans of Nyaruko:
The writing is all over the place, and most of the voice acting is uneven at best. There are so many characters that none of them have to try very hard to do a complete job, and thus they start to slack off after they’ve been introduced.
But the writers clearly get bored with the idiocy and make half-hearted attempts to write a more interesting story.
They don’t succeed, but I give them partial credit for effort.
Kanojo ga Flag wo Oraretara looks like a pretty standard romantic polygon harem show – the brooding protagonist has a convenient superpower to explain why people are so one-sidedly attracted to him, which is nice.