One of the nice things about Tahoe is that liquid glass does a better job of distinguishing controls from other elements, at least most of the time. But they need to do a better job refining some of the transparency effects to make it more consistent. For example in Safari, with a medium grey background on a page, the controls have contrast from the toolbar surface and the borders and glass effect give them a nice depth. But with a dark grey background all the contrast between the controls and the toolbar almost disappear, and only the borders give any real distinction. Its even worse on light or white backgrounds, where since the borders in the liquid glass elements tend to be light/white colored in the first place, even they disappear. The transparency effects can be nice, but someone else's choices for a site background shouldn't be having such a dramatic impact on the actual UI of the computer.

Isn't this just the principle of transparency itself?

I'm convinced what Apple is doing here has exactly one purpose: Force developers to prepare their apps for the yet to be released iGlasses so that the Apple Vision Pro situation doesn't repeat itself - a device for which no one can be bothered to make apps.

The idea is clearly that covering things with animated light-grey sludge will make transparency bearable on both computer screens and iGlasses.

They are probably right that people will get used to it, but I very much doubt that any UI designer (at Apple or elsewhere) ever thought that this design is an optimal choice for traditional computer screens.

For pure transparency, sure, but most of the liquid glass effects aren't pure transparency and there's a lot of different ways you can modulate the effect. Perhaps the simplest example of something like this is the mouse cursor. You probably don't think about it, but that cursor in macos has a thin white single pixel border around the whole cursor. On light backgrounds, it effectively disappears, but on dark and black backgrounds it allows you to easily see and follow your cursor around the screen. The cursor itself isn't changing, but the chosen design allows a single "black" cursor to work across all backgrounds.

Or the menu bar which has had a transparency effect for a version or two now auto switches between black and white text depending on the background coloring (for what its worth, so does Safari's new control bar). But in neither of these cases (the mouse or the menu bar) is the UI changing dramatically. Unlike the safari controls, when the mouse pointer loses its border, it doesn't lose depth or become harder to make out. When the text in the menu bar changes color, it doesn't switch from "popping out" to "flat on the bar". The style and overall look remains the same even as the colors adjust for the environment.

What I'm saying is that Apple needs to spend some time shoring up those sort of little touches that can and do make the UI fee thought out instead of just slapped together.

I suspect that you have got it in one, here.

They need to stop all transparency, and design with matte clearly visible widgets in mind.

Mid/late 90s interfaces were trully peak UI from that perspective.

In a world where “normal” people are calling files “v2_final_final” it’s nice to have a way to encode more information than just a file name.

Other people also use them for organization and workflows and stuff

You can see an example of that here: https://egypt.urnash.com/blog/2019/01/06/how-i-work-file-org... - it's got a screenshot of the folder of pages for a comic I was doing that had two parallel narratives, so scrolling down to the bottom of the alphabetized list wouldn't even necessarily show all the in-progress files. (Yes, I could sort by other criteria, but stuff like 'last modified date' can bring in a lot of false positives.)

I have a saved search for files marked as "in progress". And another one for files marked as both "commissions" and "in progress". All of these files might be scattered throughout my file system in various places - comics have their own folder, personal work goes in a folder named with the year, commissions sometimes end up in the yearly folder, sometimes in their own subfolder - and these saved searches let me completely disregard that and quickly ask myself "what do I feel like spending time on today".

I also have a lot of files tagged as "experiments", all saved in the yearly folder. A lot of these are the result of me sitting there on the Illustrator subreddit and answering "how do I make Illustrator do something that looks like this" questions, and packaging them up in an easy-to-reuse way; I can just look in the Experiments tag when I want to find one of them and not bother keeping a special place for them.

I don't think there's any kind of mental map going on here, the whole usefulness of tags is that I can skip navigating my folder hierarchy. Different tags very clearly mark some files as different. You can make new tags and assign them names, but you're annoyingly restricted to seven colors, so there's really not much mental mapping to do.

And you could even reduce readability by using gradients to make it fancier!

One of the reasons I continue to subscribe (sigh) to the Path Finder (Finder replacement) app, which offers whole-line highlighting (coloring) of tagged files.

(It also has a great function to batch-rename files — including with regex find and replace, and including the ability to save and load renaming algorithms.)

Not affiliated, just a very happy user (apart from the subscription licensing model, that is).