To be fair, the non-commercial license was useless in the end because the MAME team didn't have financial resources to actually _enforce_ said license. As a result, commercial uses were out there and nothing could be done about them anyway.
I have much the same misgiving, but pragmatically it's probably better for everyone's sanity to go this route as it opens up better code sharing to/from MAME with minimal to no downsides that we didn't already have.