I know that my opinion on these types of matters is generally not popular in communities such as this one, but I feel like stating it anyway...
ROM websites are not about video game preservation. They're about wholesale piracy. Sites that host ROMs for download are not doing it to "preserve" the games for future generations -- they're doing it so that people can download games illegally for free (and for the owners of the website to get some illegal ad revenue out of it at that). I honestly do not blame Nintendo for going after the owners of these sites -- they're blatantly illegal and stomp on Nintendo's (and other companies') rights as the copyright holders.
Yes, there are people who care about video game preservation (myself included). I just don't give other people access to what I've preserved, since they shouldn't have access to it under the relevant laws (both in the US and internationally). Preserving something doesn't mean making it available against the wishes of the rights holders to whoever wants it -- it means making sure that I (or whoever else I pass my collection onto in the future) can enjoy it even if my discs/cartridges were to bitrot to the point where they're unusable (as allowed by 17 U.S.C. § 117
). Preservation means making sure that servers are available for online games where it is possible to bring them back (once again without violating the rights of the individual copyright holders).
Nothing in copyright law allows you to go and download ROMs for games you don't own. Nothing in copyright law allows you to download someone else's backup/archival copy and use it (even if you own an original copy of the game). Backup/archival copies under 17 U.S.C. § 117 must be created from your own original copy in order to be legally produced.
One can argue that copyright for commercially produced works is far too long to be in the public interest (a point I'd largely agree with), but that argument doesn't change the fact that ROM download sites are engaged in widespread, commercialized (arguably, criminal) violation of copyright.
That's just my US$0.02.