Well let's stop talking absolutes firstly, Higs.
I said "strongly recommended". The simple fact is that if you don't wear one as a long-haul pilot, you run the risk of being identified as someone who doesn't support the cause of fighting to retain our jobs in aircraft with red kangaroos and "QANTAS" painted on the side. While personally I don't tend to race to final judgement until I have listened to someone's point of view (eg, maybe it just got chewed by the dog), others certainly would.
Is it "immature" to not particularly be interested in socialising with someone who doesn't support your cause or who even might be actively involved in sabotaging it? I mean, really? I'd contend that such behaviour is entirely natural, understandable, and commonplace in all walks of life. Would you go and have a nice pleasant dinner with someone who you feel might be happy to stab you in the back?