I have heard that there are sites that are distributing the old games. I even found one site that had the old Apple II games, and an emulator, for download! To the extent that Sierra doesn't object, I think it's great. Hopefully, they'll either distribute the old games, or look the other way as they are passed around the internet. I'd hate to see them just "cease to exist".
Whereas I would not post old Sierra games on this site, I am not opposed to including links to other sites here. I mentioned to one of Sierra's senior honchos a couple of years ago that I had found a site from which to download all the old Apple games, and his only comment was to say "cool". My guess would be that Sierra will never officially bless the downloads, but neither are they likely to spend a lot of money chasing people who download games that can't be found in any other way.
That said, I feel very differently about people downloading a "really old" game like King's Quest II than I do people downloading HalfLife. If a product can be found at retail, then any attempt to download it is piracy, and unacceptable behavior. I see a distinction between preserving history and piracy.