No. Bureaucracy hell is bad as well. The least amount of rules that can keep us on the sane path the better.

I'm for ban, but I can't even find any sources saying it had no effect (or the opposite). Anyone can help?

I'd be fine to wrap it into the existing smoking ban, hopefully resulting in not much more bureaucracy.

No, the government shouldn't be restricting behavior unless there is a good reason to do so.

German constitutional principles only permit restricting basic rights (this seems to affect free speech, at least in its US definition) if it is "proportional" (verhältnismäßig) - restricting only what is absolutely necessary to reach a legitimate goal.

More specifically, it has to be suitable, necessary, and appropriate/non-excessive ("geeignet, erforderlich und angemessen").

A law that doesn't achieve the stated goal would fail the "suitable" test.