The iTunes icon in 10.7 kicked it off. If felt lazy and out of place, even at the time I hated it. Then other new apps followed in the same style... App Store, Books, TV, News... By 10.15 most of the life had been drained from the icons. Then in 10.16 they went fully corporate and boring, shoving them all into their little squircle jails where they've remained for 6 years and counting.
This didn't happen before since we had shape and color to distinguish. So we lost one dimension...
And this is just because Apple is trying to merge iOS and MacOS at some point. I don't see any other reason.
It provides no info about what windows are open, it does random things when you click on an icon, it has an indicator that tells you that an app is in memory but may or may not have a window. And all these become even worse once you have multiple monitors / spaces.
Just copy whatever gnome/kde/windows are doing. All of these have figured it out. Only macOS needs an investment of like $50 per year in helper apps to deal with the poor app and window management.
Took at least 5 minutes to set it up and add the apps, then I forgot about it until now.
Just went and removed some apps that I used but don't anymore.
I know the Leopard era design is having a bit of a retro cool moment right now (frutiger aero) but for me its all about that pre-Leopard Aqua. Something very bright and friendly about that design language where the Leopard era feels a bit dark, moody, and dusky. Bordering on chiaroscuro. Especially when you compare classic Aqua to like the classic Windows look which while coming off as corporate felt like it had a precision to it (at least to my kid brain).
I have to say my hot take is that I actually kinda like Liquid Glass. It feels like a bit of a throwback to that era and dragging objects behind transparency to see the refraction was the first time in a long time I've ever just been transfixed with just playing with a UI detail. Especially since I use the Dock as bootleg taskbar (undock everything so the only things in it are the open applications and autohide), when it does pop up its fun to see everything bend around.
The touch targets can still be sane though. The click targets for the dock aren't the shape of the icons anyway.
So, after about a year or so, I defaulted to moving the dock to the left but stopped auto-hiding it.
I’ve come to thoroughly dislike the grind getting rid of them all with the dog slow animation each new Mac I set up.
But I agree with GP. The dock only really feels usable to me when it has almost nothing in it. The default is by now extremely cluttered.
What I do know is that in the uniform-looking icons we have in the current dock, I seem to find myself hunting for the right icon to click a lot more than I have in the past.
Aesthetically I think the dock peaked with 10.9 (Mavericks).
This icon goes back to the Mac Clone era when they wanted separate branding for System 7.5 etc. Kinda funny it survived Jobs and is still around.
Also, IMO there's a lot of undue nostalgia for Snow Leopard. But that 3D Dock was cool. (It didn't do that when you put your dock where it belongs, on the right side.)
10.10 onwards is pretty forgettable.
During the 10.5-10.7 era there were a number of third-party dock themes people made that worked by swapping a few image resources, which in addition to visuals could adjust reflectiveness. I had mine set to a nice studio-lit dark gray matte shelf with white 3D indicator arrows.
defaults write com.apple.dock autohide-time-modifier -int 20
so that I never have to see it.