Please don't shoot the messenger for personally I am a hat guy due to having a bald pate which is improved by any such adornment as well as the nicety of not feeling chilly raindrops on said bare area during walk arounds but alas I digress from my primary point . . .
Having recently returned from DTK and having had many a late night beverage with many UAL pilots of varied background that were attending Captain Charm School I can tell you what the corporate message was regarding hats. Customer surveys show conclusively that our customers, especially the premium customers, prefer the sharp dressed look of Barney Five rather than the cool casual attire of Sheriff Andy. No corporate conspiracy to force submission; just a carefully calculated attempt to do what they can to enhance customer satisfaction. (I know, I know . . . why give us a Clown Costume then . . . like I said don't shoot the messenger.)
Again, not that I am telling anyone what to do, just presenting what little knowledge I have that may or may not be of interest to all who peruse this most erudite of forums.