Kids in school who have behavior problems usually say no to everything. But if they think about it, would they say no to more playtime? No! (oops, i just said it). It may reduce the amount of learning they do in school, but when they do learn, they are more focused!
Some people believe kids have behavior problems because they're not allowed to be kids. It's possible that's true, but it's also possible that they really have valid issues. That being said, play can be structured in such a way that it's beneficial for children with behavioral problems. For example, a child that can't follow the rules might be encouraged to play a game that has specific rules that must be followed. Or, kids that are hyper might be given strenuous playtime to help them get it all out.
For children who have behavioral difficulties, there is no reason why the should not be given more time on the play ground. This is a much better solution to the one that seems to have been accepted by most parents today, unfortunately, which is to medicate their children into so called good behavior.
If a child has behavior problems they probably need something other than an increased play time. I get that they want to get rid of all that energy, but I do not think that really solves the issue. First you would have to address why they have a behavior problem and work from there.
I think children with behavior problems should not get more play time. I think this needs to be addressed on a case to case basis so we can get to the root of the cause. And they should be nurtured, not treated poorly like they have been in the past.