I joined in, myself.
I've always made it very clear that there is a difference between real and pretend (not just the wrestling v hurting people/fighting, toy swords v read blades -aka kitchen knives, bows and arrows v bows and arrows, toy or imaginary guns/bombs/grenades/ and real ones, etc. but also cartoons/movies/etc. and real life.... we made a point to watch the "behind the scenes" stuff on action flicks whenever possible).
This worked REALLY well in anger management / emotional regulation. There is a BIG difference (and kids know it/are taught) that yelling because someone is far away or yelling in anger are 2 different things. Jumping for fun v stomping in anger. Bumping someone in 'Hello' v shoving someone in anger. Doing something EVERYONE thinks is fun v doing something ONE person thinks is fun, and the other person is upset over.
AKA real pretend vs threats. Play v hurting people. Control v lack of control.
To ME, this kind of imaginary play is part of the beginning of laying boundaries for accepted behavior. It's a way to act out things that are right (stopping the bad guy) and things that are wrong (being the bad guy). It's experimenting and figuring out what is right and wrong, in a way that is fun instead of serious. Don't get me wrong, seriousness has it's place, I've just personally found that lessons stick better when there is a good balance. If my son wants to be the evil despot taking over the world (aka the section of woods we have to be in), he's ALSO thinking of ways that people will be trying to stop him (and that, as a matter of course he accepts that people ARE trying to stop him is pretty huge). And then, of course, we switch sides and HE'S the hero. Or we're both on the same team. (Which brings teamwork into play).
Anyhow... I think it's great. But that's just my opinion.