Again, I'm not arguing the point, and I think RockyR's SUV comparison is very appropos.

And you are very correct in the "no knees or crotch to wear out" aspect, and they are certainly more comfortable. But in my opinion, many people may balk at the initial prices because they think of the prices they would pay for other clothing that they would use for similar work, and I think that this prevents kilts from becoming as widespread as they otherwise could.