I will disagree on this as libraries pay a royalty or a one off payment to a book publisher (although it's a lot smaller than purchasing the book retail or even wholesale). Some of those titles are still for sale (Leisure Suit Larry for example), and others are in catalogs that are certainly owned by active corporations (Lemmings, Wolfenstein, Conquests of the Longbow).
Fair Use clauses generally don't allow for an entire book to be copied. Amount and substantiality are the key words and the point for copyright law (at least in the US) is that fair use is a defense against infringement, not a roadblock to being sued.
Whatever "affirmative defense" means, fair use can be viewed as a right, i.e. part of the copyright itself. Though that's some debatable subject, and has different opinions in the legal system. Regarding full or partial copying - in case of libraries fair use allows full copying, otherwise you won't be able to get full books in any library archive (which defeats the purpose of the library). Recent case with Google Books confirmed it:
http://www.lawdownunder.com/google-books-project-covered-fair-use-doctrine/Internet Archive case is a library, but I'm not an expert on how exactly they operate, so I don't know about how they deal with owners and etc. Who said they didn't pay for those, same as you said other libraries do?
About if some games are sold or not - surely, buying it is better, since you get something that you own (i.e. the purchase). When you borrow a library book, you can't own it. Same here. Personally I always prefer to buy games when they are sold (DRM-free). If some game is available for sale on GOG - I'd surely buy it rather than access through such site.
I absolutly promise that if the IP owners knew of that site they would demand their games be taken down. At the least the big companies like EA, Activision etc. I think it far more likely they don't know about it than they are ignoring it.
I'm not expecting anything else from EA. They are part of the ESA who are in general very hostile to fair use (see my link above about the
recent incident). I.e. they'd sue even if it would be for sure legal. Just because.
About ESA, see
https://en.wikipedia.org/wiki/Entertainment_Software_AssociationNot surprisingly they also supported SOPA and the like.