I've seen gyms with bumper plates and a lifting platform, clearly designed and intended for standard Olympic weightlifting style drops from chest or overhead, next to a sign saying that one should always configure the safety bars so that the bar doesn't hit the ground. This would of course damage the bar, make a tremendous amount more noise, and increase danger to the lifter. What I'm trying to say is that gym rules don't necessarily make any sense.
It's perfectly reasonable to drop a bumper-plate-loaded Olympic bar from chest or overhead in a controlled manner while using an Olympic platform: guiding it down with the hands, making sure it doesn't bounce into the wall, and so on. That doesn't mean everyone at the gym will understand or accept this normalcy. It may even be technically and bizarrely against the rules at your gym. Whether or not it's rude is determined by how knowledgeable your fellow gym-goers are with Olympic lifting, which is to say that it defies all reason and pattern. The guy who doesn't unload his bench press, loudly sings along to his earbuds, curls in the squat rack, steals people's weights while they sit and rest for thirty seconds between sets, and gets his sweat all over the floor might consider it rude for you to drop a 1RM snatch or bail out of a failed max clean & jerk. C'est la vie.
Dropping a bar only becomes problematic when it is excessive or unnecessary. Letting go of every deadlift, including warm-up sets, is one example. Dropping a light overhead press is another. Slamming or pushing the bar to the floor in celebration is another. Dropping the bar should be done because it wouldn't be safe for the lifter to do otherwise, which is common in Olympic lifting and occasionally with other lifts. Dropping a bar to avoid the increased soreness that comes with lowering it as well as raising it is a fuzzy area that should take into account the disruption to one's fellow gym mates, but dropping a bar for safety is just something people should get used to as part of being in a place where weights get lifted overhead.