Agreed. I used to be really into customization and I get that there's a certain pride and sense of accomplishment and sense of ownership that goes with it.
But there's also a certain zen to just declaring bankruptcy on configuration and tweakery. Gnome used to bother me (and Ubuntu did too) but I've learned to just let go. If I can't figure out how to change something in a few seconds, it's probably not worth the effort because in a few years or months I'll be under configuration debt.
Tangentially, as an example, I switched to this launcher on Android called Niagara. The developer refuses to make categories/folders to group apps. And it made me so angry at first. But he also made it really easy to rename things and the launcher's key feature is that selecting things alphabetically is nearly instant. The problem was that I could never remember what things were called. Like... what's the name of that god damn app that opens my garage door? And I'd hunt for it all over and curse the fact that I couldn't put things in a quick folder. And then I realized I could just... rename the app "Garage Door". Who needs categories. Ok prefix games with "Game - " etc. All the dumb apps my kids schools require are prefixed with the kid's name.
Now, that does still sound like putting effort into configuration. But it's just one feature and the payoff is not having to even think about things ever again. And there's no configuration debt because it didn't take as much effort in the first place as you'd think. If I don't find something quickly, then it needs to be renamed.
Well that rambled a bit, but the point is that just because I know a complex way to do things (an elaborate folder structure of apps in the old launcher that I used to have to constantly reconfigure and fuss about because even then it was difficult to find things), maybe there are better ways to do things. Like Niagra's method to scroll through all the apps fast as hell and now I never think about how to organize icons.
So sure Firefox was one way decades ago. Chrome is different and does things differently than Firefox does. If people are willing to declare bankruptcy and switch to Chrome, why not be willing to declare bankruptcy to the same features and allow Firefox to evolve?
... does Chrome even have an equivalent of this compact view? In the big picture, shaving a few pixels in a browser theme seems like the wrong reason to choose a web browser. Too much bikeshedding.