Actually this is intersting. From a programmers point of view I can see the trouble being discussed.
However, this also got me thinking about some other aspects. As some may know, I'm part of a arcade and pinball museum. We got about 200 machines running, and quite the same amount "to do".
So I got a WingWar machine which was submerged underwater for quite some time. The boardset was damaged beyound repair, so I "MAMEd" it. Part of this process led to some "interesting developments" regarding network emulation.
My point is, now that I think of it, I'm unsure if that use of MAME is violating the license. And I'm not talking about the ROM issue - I was able to dump my boards.