Clothing companies should offer their expertise to the space program. Fashion and space have a long history of working together. There are a lot of talented people in the industry that can provide guidance on the proper suit to wear. They can help provide suits that are not only more comfortable, but also increasingly effective.
Space suits should be designed by clothing companies, but only if it meets the most stringent safety standards possible. While clothing companies generally intend to capitalize on fashion trends and market desires, space exploration is anything but. Astronauts don't care what they look like. They care about coming back home safe and sound.
Scientists understand what it takes for man to live in space for a while and right now they know that in order to survive in space you need a suit that, although it may not look the most comfortable, will keep them breathing air and not dying. Also bringing fashion companies is not necessary at all because only a few people are going into space so I doubt they care that much about what they look like.
I do not think that future space suits should be designed by clothing companies. It would be better if they leave that job to NASA. In my opinion, space suits are very different from regular clothes, so only professionals who know a lot about astronauts and their needs should make them.
Future space suits should not be designed by clothing companies. Space suits are created to protect those who wear them from the elements, or lack there of, in space. Scientists work to ensure that these suits create a safe environment for the user. Clothing companies do not have the type of knowledge, and would not be able to accurately manufacture an effective suit.