I agree that seemingly negative emotions can be great fuel for creativity. In my off time I write poems and man - when I am angry, I can really rip off a good one! Or when I am disappointed or frustrated. I think feeling angry can also prevent people from feeling other emotions, as you mentioned, and so some people use it (anger) as a sort of shield.
Personally, I don't like feeling like I'm reacting angrily. I have some friends that will get very angry about things, but often it seems to me like a lot of energy that isn't always worth it. Of course, it depends on the situation - there are times when it's completely legitimate to get angry, or at least, a reasonable reaction. (my post about my brother springs to mind.) Haha, I guess it's a toss up. I try not to get angry about things that are completely out of my control. This morning for instance I received a rejection for a poetry submission. That's not worth getting angry or even upset about; I can't control whether other people like what I write or not, and in fact it'd be silly to assume that everyone who read it did!
I think it would be interesting if there is anyone in the crowd that practices meditation or other mindfulness exercises, if they could speak up and talk about anger in their life, I'd be curious to hear about how they process it/deal with it. Unfortunately I don't know, off the top of my head, of anyone on Hubski who does, so I can't call anyone out and ask them.
This, and the end of your post, reminds me of those stories about mothers/parents of middle-to-high school kids that have gotten online and bullied their students' classmates. I have heard of this happening at least once and I think it's a repeated phenomenon. Sadly, if you are a grown adult with children behaving in such a fashion, I don't think you are going to grow out of it. But how do you address such an issue, except when the behavior gets so extreme it's already significantly harmed someone (by the time anything like this gets to the courts, where people can be punished for their 'trolling' or internet bullying, usually someone has already been hurt pretty badly - I'm thinking about the kid(s) who have committed suicide partially as a result of internet bullying here)?