I have recently discovered the same issue with one of my wordpress blogs that is using a different seo plugin than I typically use. It seems as though it has the plugin has the ability to generate unique titles and descriptions based on the name of the tag, but for some reason on this particular one.. it is not.
I can't speak as to how beneficial it would be to have these optimized vs. no-indexing them. I suspect it depends on how the tags are used. For some wordpress sites, having a tag archive appear in search results may not be of much benefit, while others may be a different story. I am interested to see what others have to say about this, but for me personally the tags are more for organization internally and to identify similar content which I display on the blog page and not so much about having another page I am trying to get indexed. Simply put, I have bigger fish to fry...but that is just my opinion.