While there are a lot of questions that don't show it, I believe the tag can have a good use and that it is useful in certain scenarios.
I do think the tag definition should be altered because we have tags for most common instruments so the current tag definition is not useful. I would change the definition from:
Questions about an instrument itself, rather than how to play it.
For questions about generalities about instruments or groups of instruments.
I've alway kind of been using it the second way as seen my question Alternative ways to classify Instruments which is where that tag in my mind really fits. There are other questions that I can think of that would make use of this tag that have not been asked yet including:
- What instruments use the tenor clef?
- Is there a certain way to arrange instruments on a score?
- Why are bass instruments typically bigger in size then other instruments?
There's not really an appropriate tag to talk about each individual instrument in the proposed questions above and we're referring to instruments in groups that aren't very common so instruments would be very useful in those scenarios.