I took the girls all around the US, around the world even as they were growing up. I had grown up in a “camera family” so always had one on trips as a parent too.
Now, with two decades behind me, the photos of my young daughters, wife are the vacation photos I return to.
Oldest daughter is wearing a kimono sipping tea at some place in the mountains of Japan… Two youngest are chasing each other on the beach of some island in Hawaii…
These are not achievements, or unusual places, or humans. The things I'd like to see are stores of subtle cultural information than gets lost because it seems unimportant, and then a couple of decades later I want to look at all the details of it again but I can't. What was that car I used to be slightly interested by every time I walked past it? What range of items used to be for sale? What books did I have? What was actually on that poster that got torn and thrown out and now it's impossible to find another? Instead of answers, I have holiday snaps and pictures of humans.
You mean in the sense that no one sends/receives them? Because that might be true for the younger generation, but postcards are still available literally anywhere I've been in the world, and are still very easy to send, for those who enjoy that.
I mean both that they are used much less and they're much less available.
You can find postcards of the Coliseum in Rome, but you'll have a hard time finding one of Palazzo Farnese in Caprarola.
Even in major touristic hotspots, 30 years ago you'd find postcards sold at any shop, but these days you have to look for a while, in my experience.
I've been to some countries where only the official post office was allowed to sell stamps. That makes things much more inconvenient than the shop selling postcards also selling the stamps.
It made some sense to take pictures of panoramas or art when you could show something to people that could not see it otherwise, but in this era it makes no sense (unless you enjoy photography as a hobby).
A goofy picture of you kissing some old bronze statue? Dumb, but yours.