WIY: Not true. $90 is way too expensive for a skirt imho. But if it’s tznius, and people will wear it instead of less tznius denim skirts (and knowing women’s styles that is a strong possibility) I don’t think it’s a bad thing.
I personally don’t wear denim, but there is nothing essentially wrong with it.
be good: denim is not even that fashionable any more. but you’re right that to each their own.