I absolutely agree that that's a loss, but that argument would seem to apply equally to all online games. But a game isn't less worth playing because it's online, right?
One solution may be to propose an escrow system.
A neutral non profit (or several) sets up an entity which exists to collect software binaries and/or source code from companies under strict NDA.
At some event, either after a period of time or at the time in which the service based on that software ceases to operate; the software is released to the public (either for free or for some payment to the escrow entity).
In return the company gets a "no abandonware" sticker it can use in it's marketing/branding which gives consumers confidence in their purchase.