I just signed up here (having used discourse on the quite active MaidSafe forum for about three months) to suggest exactly the feature quoted. Nice that it was suggested just yesterday 
I don’t use stars much, but I have 96 bookmarks - all posts which contain important nuggets of information - but which I now can’t really access. All the while I was thinking, I need some way to organise this - e.g. to tag them as I go: encryption / authentication / farming / app-idea, and so on. Ideally multiple tags per post when I need that, and then to be able to list my bookmarks and filter by tag.
I just learned that discourse has plugins, so forgive me if this is available that way. If it is please say and if you can point me to it please do.
If discourse had the feature I just described, it wouldn’t need stars as well, though its not an issue for me. I don’t find the UI too cluttered and I can imagine some people would like to have star as a “special” way to mark posts, or perhaps as a way to have some other functionality not available with bookmarks.
Also want to add that I really like discourse and we get about one new person a week turning up and going “wow, what is this software, where can I get it, is it open source etc.”