I generally agree that anger isn’t usually the best emotion to use or actualize. Especially for me — my anger usually feels more destructive (internally and/or externally) that really useful.
But my opinion has shifted just a little bit when I read Terry Prachett’s “The Wee Free Men” and there’s a scene where the main character (Tiffany Aching) cultivates her anger at threat to her home and its safety as a means to combat her fear, which allows her to take action against the threat. And I think this kind of anger — used as fuel against a threat or danger to something or someone precious — is the kind of anger I think David Gerrold was talking about.
So, to me, it’s best to understand what anger means to someone and how it functions in your life. For me, I don’t think using anger is probably good for me. But if your anger serves to supplant fear so you can actually act, than do that, if that’s what works for you.
Though I suppose the biggest danger of anger is that, as you said, creates blind spots and can limit understanding. But as part of a fuel for resistance, it could be useful for some people, perhaps.