There is a bunch of windsurfers doing longboard windsurfing in waves. They do not always have footstraps. They are SUP boards with a mast track and its done normally when the wind is light.
But for shortboards and planning and high winds, I doubt it. The gains in having footstraps would completely out weigh not having them.
Waveslave, this is probably the most impressive example I've seen:
www.seabreeze.com.au/forums/topic.asp?TOPIC_ID=36961
Velcro deck, and sail in socks.. Interesting idea!
No more falling out of the straps in mid air.. and no more adjusting the size or position of the straps - just stick your foot somewhere else..
pretty sure Laird hamilton has done this in a surf movie back in the early 90's, he used booties with one side of the velcro on the bottom and on the board he had the other side of the velcro, looked like those old full deck gorilla grip, he paddled in like a normal surfer and once he jumped up was stuck to the board, showed him doing back flips off the lip and landing back on the face again, looked mad fun..
The guy doing the backloop just has those sky hook things front and back - like ollie horns on an early 90s skateboard... And you can see he has his feet firmly in them during the loop
if you want to power some good moves.
you need to be attached to the weapon.
next thing someone will ask whether you sail unfingered.