Every time I create a a new instance configuration, I can add tags to it. But it want's me to create an all new tag, instead of picking one from a list (or loading the list as I type the tag name, which I shouldn't have to do anyway).
The global part comes in that if I create an instance tag, it should apply to all servers, at least at creation or editing time. Making a tag mandatory would be swell, but that might be another enhancement request one day..