I had the pleasure of watching the Blue Angels do their thing recently at their winter training ground. They were very impressive and always made the effort to wave whilst taxiing past. They also came to visit my unit, in preparation for a display, a couple of months ago and the crew came wearing boom mikes for the transit.
There can be no reason other than aesthetics for not wearing a mask. This is just a case of risk analysis (or not) resulting in a course of action. There is no reason why a mask could not be worn for this stuff and not wearing one brings risk both for ejection (low probability) and smoke and fumes (low probability). Imho suggesting that it's for range of motion or weight is (imho) misguided. We do defensive BFM with masks and JHMCS very often which requires greater range of motion; max available G; and greater weight on the old head. It's no big deal.