Some people want to play with playsets. Some people want to display models. Some people want to create art. Some people want to construct machines. Some people want to assert allegiance. Some people want to collect.
All of these aims are valid. The diversity of ways to buy LEGO supports them all, while maintaining a high-quality, largely compatible, reasonably consistent medium.
In the 1990s, it was a "construction toy" first, playset second, display model last. A kid could take any set and rebuild it into something else in an hour or so. Now, they would need more time only to sort the tiny 1x1 pieces before starting to build anything.
The "voxel sculpture" style where you just stack (mostly) rectangular bricks into a shape is perfectly valid, but it's less interesting to me personally.
Modern Lego supports both. Both are valid. They still sell big brick buckets, and no one's stopping you from buying one of those and doing your thing.
https://www.lego.com/en-us/product/lego-large-creative-brick...
Still though, I just might have to top off the kids collection with one of these boxes. Good find.
I think there is an actually an "addition" here rather than a change. You're an adult conversing with adults (I assume) and therefore the discussions you have and the marketing you see are more about sets targeted to AFOLs (Adult Fans of Lego).
The classic Lego childhood lines (Lego City) still exist and still work just as well for play and creative construction as they ever did - and they don't use a lot of 1x1s. It's just that we've also gained these new lines of large adult sets that never used to exist.
In the 1990s, Town vehicles were 4-stud wide and didn't focus on the small detailing. The instructions for the original vehicle were just a single sheet of paper with less than 20 steps. You could build the original vehicle by memory after having built it a couple of times with instructions. The back of the box suggested alternative builds, which, although looking "imperfect" were a solid base for imagination.
The kits don't stop him from just building his own stuff either. The two forms of play seem complimentary.
Once they've got a few sets like that, the rebuilding into unspecified stuff seems to come naturally (at least with the cousins and friends kids I've played with).