I'm all for a "green" sales/delivery model of downloads only.
I'd estimate that 99% of all software I purchase now is downloaded.
The one exception is Band in a Box.

The main reason is size ... I have a fast cable connection but I can't see myself DL'ing a gazillion RealTrack files. I just don't have the time for that.

As far as old BiAB hard drives go - I keep the last version around just in case something happens to my current drive. And the drive before that I've turned into my carry-around "off-site" data backup device.