For most games it'd be pretty much useless... But in medium and large scale milsims (something like 80 and more, so the used field area would have to be quite large) as well as maybe some other specific scenarios (MOUT?) it could add something.
Now... at 15 000$? No way. For that price you can get 2 used pickups with an M249 and maybe even more if you find some good deals...