A lot of the fashion advice giving by the various associations are needed in order to A) have some uniformity among officials without having to constantly call each other before games, and B) keep some of the less well-dressed from completely looking like slobs.
But it seems every association has 2-3 items that they insist on for sheer fashion snobbery. Fitted vs flex-fit hats is one of those for ASA. It doesn't really matter. The only people it matters to are people who are just wanting to invent reasons to decide one official or another is worse than them... aka fashion snobbery.
Had a fellow official get snobby over my football whistle 2 weeks ago. After a good 2-3 minutes of him lording how wonderful his whistle was and how bad mine was, I just said... Can you hear my whistle? He said Yes. I said, Then lets move on, ok?
Rant off.