It has nothing to do with who was watching when. The notion of performing duties in a skirt is ridiculous. Ask anybody who has to do any form of manual labor (like realigning sensors, crawling in a Jeffries Tube, or performing calisthenics) in the real world and they'll tell you that a skirt is hardly the easiest thing to work in. It's like working in high heels or in combat boots if you're a sever at a restaurant. It's just impractical and doesn't take any advanced form of knowledge to figure that out.
Who says this crewman has to crawl through tubes?
And I think you didn't get what I was saying. People from the 18th century looking at our fashion would find it utterly ridiculous. So it would just be realistic if Trek characters wore ridiculous stuff. Above all it is
supposed to be a Science Fiction show.