We've been having a very large discussion about this on the IGDA preservation SIG discussion list
http://wiki.igda.org/Game_Preservation_SIGWhat it comes down to is that Jason Scott, at Archive, is fearless. He saves EVERYTHING. If you think putting these MAME ROMS on Internet Archive is ballsy, check out what else he's put on there: https://archive.org/details/tosec
The standard policy, as he explained it to me, is to put it all up, and if someone complains enough and gets enough lawyers involved, the individual file cited is removed, not the whole damn archive.
Why brave the lawsuits? Because about 10 years ago, Aardman Animation( http://www.aardman.com/ ) makers of Wallace and Gromit had a catastrophic fire in their archive building. The fire destroyed a large portion of the stop-motion animation studio's history. A lot of the stuff destroyed was not preserved anywhere else, and is thus, now, lost to the world forever.
Since videogame companies are acquired at the same rate as radioactive particles are emitted from an element with a half-life measured in seconds, it's very common for a company to go under and for the acquirer to just dump everything in the trash, save for the very non-physical IP rights. I've seen what game companies throw away, and even discovered entirely unpublished, unknown yet finished games ( http://www.atariprotos.com/2600/software/cpk/cpk.htm ) because game companies don't care about old assets, only old IP.
The next step in this effort is to preserve the source code behind these games, but that's a far more difficult proposition, and most of the code that's out there was deleted long ago.
It's our collective cultural heritage. We have a right to preserve it if the original creators or owners can't/won't. Rather than pick and choose what to save, Jason Scott saves everything. That way, nothing is lost in the cracks of history.