Entire styles were born out of the sounds that came from multimicing and experimentig with those signals. It doesn't matter if it's one instrument, it's an artistic choice that happened because of necessity and now it's the standard way of doing things. Try recording metal drums with one mic and getting it to be heard and have impact in the mix. There is no only one way of doing things for there are different things to be achieved. And that's the beauty of record production.