To me it's not what you necessarily wear "for" the flight, its where you have been and where you are going when you get the other end!

I flew (in F) DXB-IAH-DEN 3 weeks ago in shorts, smartish shoes tee and a shirt over it. All was fine, till i got to DEN, we arrived 4 hours late, 11pm, it was dark, and cold, i still had my shades on my head and looked ridiculous

I have worn shorts and got bumped at the gate and at check in. So I really do not think EK judge you either for what you wear!

I flew to BOM last week in J and got bumped to F in the lounge, wearing shorts and same thing on the way back - I was the only one in shorts in a full cabin, no one cared - least they did not aqpproach me and ask that i use a blanket!