Firstly, I come from a road background, I would never wear anything other than lycra on a bike. I'm happy walking through a city to collect a bike in my Castelli cycling tights. To me it's pretty natural, so this is not an anti-lycra mindset.
The right clothing is important. So is looking good.
I just can't see myself pulling off tights and trainers on flat pedals riding a hardtail through singletrack. It would look and feel like doing a sports class in school shoes.
I want to stay warm for maximum injury prevention, dry for comfort, and still look good. Road cycling is a no-brainer, but for MTB? Shorts would be too cold. The only valid option seems to be some kind of DH pant (Fox etc)?