So what? It makes absolutely no difference to anything. The Moon isn't exactly an ecosystem.
Nor is the Earth orbit, for the case. Problem is that all that trash that we leave out there is coming to bite us back sooner or later. The Earth orbit is a worse case than the Moon surface as it is a lot more "populated" and it has a lot more (and more dangerous) trash that can impact any valuable satellite or space ship. There is a lot of dangerous sized trash that is being tracked, but there is a lot that is not tracked at all, not to talk of "unknown" origin one, a.k.a. military/spy satellite debris.