If you don't want kids in there, don't have kids in there. Your choice.
If you want kids in there, then have them in there and drop your own personal Game "communist" at the door and let your inner kid out. So what if you have to vaccum and wipe down your controls afterwards? You just made a lasting memory for some kids. That's priceless.
If you allow kids and make an oppressive rule list and run around like a british nanny the whole time, be prepared to enjoy your gameroom alone after the first game night.
I have kids, so I make a point not to own anything I'll cry too hard if it gets a little scratch. It's gonna happen sooner or later.
Tapping out a rhythm on controls? Really? I do that all the time while waiting for a ball.
Now if a kid is outright abusive, then absolutely give them a warning. I don't tolerate abusiveness such as punching glass, slamming controls, etc.