I like the tag serial. It is about as useful as the tags software or microcontroller, which, while valid tags, need to be used sparingly, only when better, more specific tags are not possible. Unfortunately this hasn't happened: 180 questions have been tagged microcontroller (only 26 have been tagged software, which, for a site that isn't supposed to be about software other than DSP, I still think is high).
There are currently 40 questions tagged serial -- a large chunk considering the relatively small question base. Many of them can be more appropriately tagged something else, or additionally, but not all (or even most) to uart. Change the ones that don't fit. If someone doesn't like your edit, they can edit in turn.
I think those of us that edit often will go through a period where users will disagree with many our choices and make changes on their own. It is important that we don't take this personally, instead embracing the exchange as a debate between peers. Reminds me of Wikipedia... if someone is a regular from that community, please provide tips!