While I do greatly miss the ability to theme, I'm not sure it would work with a modern architecture. You used to have window "Chrome", titlebars, borders, buttons, etc as very distinct and separate from the window content. Now the line has blurred greatly. On top of that, the number of cross platform apps has increased so even if you could control the bog standard apps, things like Slack wouldn't follow.
This last bit used to be a big problem with Linux, if you ran a Gnome theme, and fired up a KDE app, it was like an alien suddenly landed on your desktop. Statically linked apps were often worse because a static linked KDE app wouldn't even have the same theme as the dynamically linked ones. Java based apps, apps built with other toolkits, all added their own unique and clashing bits of chaos to your interface.
One of the upsides to MacOS, is third party toolkits have a single target look to try and mimic.
Even so, I still miss being able to theme. The recent post about Mira Furlan passing reminded me of a Babylon 5 theme I wrote for Windowmaker what seems like a lifetime ago.
This last bit used to be a big problem with Linux, if you ran a Gnome theme, and fired up a KDE app, it was like an alien suddenly landed on your desktop. Statically linked apps were often worse because a static linked KDE app wouldn't even have the same theme as the dynamically linked ones. Java based apps, apps built with other toolkits, all added their own unique and clashing bits of chaos to your interface.
One of the upsides to MacOS, is third party toolkits have a single target look to try and mimic.
Even so, I still miss being able to theme. The recent post about Mira Furlan passing reminded me of a Babylon 5 theme I wrote for Windowmaker what seems like a lifetime ago.