I'd be interested to know what effort would be needed to decouple the manual download database from what is connected to WU within currently supported versions of windows, presumably they've already got some way of filtering off which drivers they want to keep live. I think MS could handle the download cost of old drivers when a lot of them can be smaller than an average modern webpage.

I guess it comes down to the question of how much MS cares about old hard/software past its support window, versus delegating that to third party sites like vogons.org and praying someone has the relevant file still available.