I think allies even get your culture bonus, but I'm not sure on that.
You can be sure about it now, because that is how it works

Any friendly culture will raise allegiance and all the appropriate culture stuff. Doesn't have to be your own (or the AI's, in this case).
It was fun though in beta when allies' culture stole your planets. Okay, no, that part wasn't fun. It's when your culture flipped your allies' that was.
who do you contact to suggest it to the bata developers?
Post it somewhere. But this kind of thing has been suggested many times before the game was even released.