Very few people would want ANYTHING to run on an email!!
Oh yes. That would be a VERY bad idea
IIRC, some past flavour of MS Outlook (not Outlook Express, btw) would autoexecute javascript, until several e-mail nasties came along and Microsoft realized that it was a bit of a silly idea. There are enough people who still click on "not_a_trojan_honest.gif.exe" when it arrives in an e-mail from a complete stranger. Having whatever they decide to send you autoexecute would be far worse.