That's an interesting question. Perhaps the 1970's hip factor killed the geek image from the 50's and 60's. There was a lot of fashion rebellion in that decade (and thankfully, most of it is gone). At least the skinny tie made a comeback in the last decade
Today you really only see short sleeve button downs as very casual. Wearing a tie with a short sleeve shirt is ok only if you're 16 and working at a grocery store...but it's a look I wouldn't be caught dead in.
Actually, you'll never see me wearing a tie without a sport coat or suit either.
I nearly always wear a coat for business, and I agree it's brutal, especially as I travel down south a lot. During the worst of times I'll actually take a coat, carry it around and quickly put it on if I need.
I'll look around and see what I can find.
-spence