Remember the shoe bomber? How far do you think that joker would have gotten on a naked airplane? Actually, I don't think he got very far on a normal airplane either, if memory serves, but he'd have gotten even less far on a nudie plane. Mmm, that's good grammar.
Because flying is often more of a chore than a pleasure, with all its cramped seats and poor food choices and tiny bathrooms and SkyMall catalogs, a German airline decided enough of this s**t! Or, to be more accurate, scheisse! Let's force people to sit cramped and uncomfortable next to naked strangers. I like to think that the moment in Fight Club when Brad Pitt gets up and debates which is more polite, passing ass-first or crotch-first, would have been infinitely more exciting on a nude flight. Plus what are the odds no one is leaving a snail trail on the upholstery?
For safety reasons, the flight crew must remain clothed, because ... there are so many jokes I could end this sentence with. If you're not sure what kind of safety concerns require a stewardess to remain clothed, well then, you've clearly never been on a nude flight when a series of very unfortunate incidents took place. I like to think they involved nipples getting stuck in overheard compartments and maybe explosive scrotal decompression.