We had hats, then the company decided it was too expensive, and so stopped ordering them for new hires. Also, not many wore them anyway. Then a memo was issued saying they were optional. Curiously this somehow prompted the remaining crew to take up hat-wearing again!
hmmm
ps. I think a traditional pilot uniform looks incomplete without one, like you forgot it in the car. Newer looks with leather jackets and such do just fine without them IMO.