You're better off heating with a heat pump—it's about three times more efficient than resistive heat, which is what you get out of a light bulb. Of course, if all you have is resistive heat, you're right that it makes no difference, but people who live in cold climates typically don't use resistive heat because it's so bloody expensive. We use oil, or gas, or heat pump, or wood, or some combination of these.
Heat Pumps don't work when it's below freezing.
If you have a brain, you got rid of those fucking things more than 5 years ago.
It would be a pretty stupid thing to buy and expensive LED or other bulb to put in a crawlspace, or attic, or even a closet. Payback will never happen. Not enough energy used to make a difference either.
I am not an Electrician, but I'm pretty sure that you aren't supposed to use incandescent lights in a closet because of the fire risk involved. An attic or crawlspace, which will have exposed insulation and other combustibles that aren't behind a firewall (Drywall) like the other parts of your home, probably shouldn't have those in there either. It produces a very real and tangible safety issue. House fires started in concealed places are the worst as you can be in your home and not notice until it's too late.
While you use these for a short amount of time, it is easy to leave one on. Just spend the $5-$25 for the remote possibility of saving a $100,000 - $1,000,000 structure.
Like that Intel NIC that was reliably going offline when receiving a "corrupted" packet?
Suffice to say that this is one of the times that, "It's not a bug, it's a feature" wouldn't apply.
"If I do not want others to quote me, I do not speak." -- Phil Wayne