Because it feels good to have the sun and the wind touching your skin!
I think in order to answer your question you need to get naked and spend a week in a nudist resort.
They want to be nakey with a bunch of other folks...I suppose.
No idea. :D
Because it is a great experience.
Going nude in a social setting is very pleasant and freeing. Also, to my experience, most people are much nicer and less pretentious when their genitals are in plain view. There's a lot more which I could say, but that get its, I think.
Couldn't find the right size in the swimming suit shop.
The extreme relaxation is worth it. Being naked only feels odd for the first five seconds. Everyone is polite and well behaved. The hardest part is getting dressed when it's time to leave.
I agree with the relaxation part.Being able to lounge naked by the pool is wonderful.We pitch a tent at the nudist and clothing optional venues we visit.It is so nice not having to put pants on if you need to leave the tent in the middle of the night.I really enjoy my naked time in the sunshine.
Lack of a proper wardrobe.
For indecisive people it's a no brainer: no pressure to pick out today's outfit! :P