In my experiences growing up, if something was fully restricted, it made me: a) really want that thing (happened a lot with tech) b) develop really unnatural aversions to it (a religious upbringing made this rear it's head in a lot of plays)

So my (completely amateur) opinion is to have a policy like you're doing, but only enforce it like 80% of the time. 100% is where you start to get into giving people complexes territory.