I haven't gone through the games they have, but it makes sense to preserve ALL games for future generations. I'd even go so far as to offer games in an original variant; but also in modified variants, aka one being mostly focused on fixing bugs and doing modest upgrades (simplifying playability and SLIGHT improvements to the user interface), as well as slightly more aggressive upgrades, including UI, making them visually beautiful but retaining the spirit of the game. For instance, of all the simcities, the first one was IMO the best. The graphics lateron were much better of course, but playability wise I found the first one the most addictive; similar with colonization, first one was quite good. The last 3 releases had better graphics, but playability wise it felt like 100 steps back.

What I would love to see is that we retain old flash games too. HTML5 was promoted as "making flash obsolete", but they never fulfilled that promise. Many flash-games simply died and there was no replacement in HTML; similar with some java applet games. Or at the least I could not find a replacement (that's also a problem - with google search having become nearly useless, finding things is super-hard; and of course old websites tend to die, that is also a problem).