Probably because that is the direction mail is going. If you can't do it too bad, but don't expect everyone else to wait around for you to catch up. Time to move your mail into the early 90s and get a MIME-aware mail agent...

Ah, a refreshing sentiment ;) There is an EXCELLENT article in this month's Scientific American which touches upon this issue. "Ensuring the Longevity of Digital Documents". It mentions how a Shakespeare sonnet written four centuries ago is still readable. Data stored/formatted in completly cutting edge ways from a decade or two ago is in danger of becoming unreadable. (8" floppy disks, paper tape, CDC 876 mag tapes anybody?)