I don't mind the occasional bat flip for a HR in a big moment. But yeah, celebrating every base hit is just annoying IMO. I always like the advice that when you make a good play (or hit a HR, score a touchdown, make a 3-pointer, etc.) you should act as though you have done it before, not as if you just surprised yourself and your teammates.
No youth or HS team I know of would allow this kind of stuff today. But I assume this behavior in MLB eventually will trickle down to other levels--it always seems to.