I am a millennial, I my dad was brought up by boomers. Growing up, those little rules of etiquette were drilled into us. Like, you never showed up to a party empty-handed, and saying "please" and "thank you" were non-negotiable.
It's definitely interesting to see how things have changed. I think a lot of it has to do with the pace of life speeding up and the emphasis shifting from formal manners to, well, just being a decent human.
I still try to hold onto some of those old-school values, but I also try not to be too judgmental. Maybe it's just a different generation, with different priorities.
I do wonder sometimes if we've lost a little something in the shuffle, though. That sense of respect for others, even in small ways, can go a long way.