Not all discarded computers are PCs. There is a lot of history that could be permanently lost if it's not deliberately preserved.
I keep a couple generations of Apple IIs, an 8-bit Atari, Amigas, RISC boxes and Macs (a couple months back you could see a perfectly functional Mac SE as part of my living-room decor) preserved. Lots of other important machines have been destroyed or recycled. I try to do my part preserving a small part of our heritage.
Believe me, there are enough people hoarding old computers. I could find all of those in my dad's basement. There is an official computer museum, we have our bases covered.
There is no "official" computer museum in my city. There are a couple private collectors with interesting artifacts and there is a group that is trying to establish a "real", curated, computer museum, but so far there is nothing definitive.
You also know not everybody lives on or close to Mountain View ;-)
You should also take into consideration all geographic differences in computing machinery. There were computers in Asia, Eastern Europe or South America that simply are not available elsewhere. A friend of mine has one of the few Macintosh clones (68K, Fat Mac-like) ever made and from that machine we can prove Apple's allegations to the DoJ against the Brazilian manufacturer were false - they removed the reverse-engineered ROM and put an original ROM inside the machine in order to show they were copies.
Those little moments will end up lost if we don't take care.
If we fail, one day our descendants will sing songs about the Whalers on the Moon and their heroic exploits.
