I'm kinda torn on this one. No one should discredit the work the MAME team or others in the emulation scene have done but on the other hand, how much of this work would've been done had it not been for all the copyrighted games/software that was dumped and used? I understand that some of it was done legally by owners of said hardware/software but the overwhelming majority of this material has been dumped/passed around through less than legal means. We've all benefitted from the work of both sides.
Seems like a wash too me. MAME's mission was always to preserve this stuff for future generations. This development changes none of that.