I can understand that you might be surprised that during a 14hr sector none of the crew have been to visit the cockpit but do you realise what is happening in the cabin?
1. some pursers still discourage movements by crew between cabin classes.
2. for example a SYD/MEL trip all crew are on duty for the first service and then half go straight down to the bunks for their break. During this time the remaining crew are kept well busy clearing up, doing preps for the next service/sector aswell as maintaining the cabin they cant afford the time to visit the flight deck and leave the other crew alone. Then the break shifts swap over before its all hands on deck for the final service before landing.
As for some of your other points it goes both ways believe me. Ive also been ignored by flight deck crew in hotel lobbies, or could it be that people do look different out of uniform and they've not recognised you?
Dont take any of it personal. Im not a person big on attending the crew dinners because after spending that 14hr sector, the last thing i'd want to do is go for dinner with the same cabin crew. Although i always make a point of thanking the tech crew at the end of the trip rather than being the 5th person to shout out loud on the crew bus asking how many flying hours ive just accumulated!