I had an Apple Network Server that I got for $75 from a company that lost the AIX disks for it. I pimped the processor and RAM and stuffed the drive bays full of scsi goodness. I ran it until about 2005 when I switched to RAQ2 which was actually more powerful, had more hd space, and used less power. I used the ANS as a print stand until about a year ago when I needed more space and replaced it with a tool chest cabinet.
It saddens my that there is this tipping point where it becomes more wasteful because of power consumption to keep using old technology. It would be completely against tech companies' bottom lines, but the earth would love it if we could create an upgradable platform with a multi-decade usable lifespan while still being efficient.