> they're still figuring out what it's supposed to even be
"It" can be any distro. GNU/Linux distros aren't a single entity, and they never will settle on a common interface---that's a good thing. Larger distros like Ubuntu will, but if you're going to adopt this perspective, you'll need to start thinking about the individual distributions and companies/communities behind them rather than "the" GNU/Linux desktop.
Not if you're looking for a macOS alternative. I'm fine with the "distros" doing what they want. However, that is not going to lead to a cohesive experience of the kind that macOS is able to provide.
A bigger problem than the desktop environment may be that apps are written to different UI toolkits (these days mostly GTK+ and Qt), and the different environments provide themes to get a unified look. Most apps aren't targeting a particular desktop environment, and so you get this inherent tension, where it's "unopinioned all the way down" and nobody makes a clear decision about a unified look/feel to anything.
I can see why a certain group of hackers like this jangly mess where a lot of time is spent on customizing stuff to work exactly the way they like it, being able to choose a completely different "window manager" and so on. I was like that in my early years, and today I just want things that work. What I want is consistency and stability with a mind behind it. I want it to boot up and render high-quality, subpixel-aliased fonts, and then I'd like to get right to work.
The KDE community seems more closely aligned with this idea, but they still don't control the apps, and unfortunately they still seem to be stuck in the Windows 2000 copy machine mindset.
> A bigger problem than the desktop environment may be that apps are written to different UI toolkits (these days mostly GTK+ and Qt)
I can agree with this criticism (granted, I don't use many GUI programs)---not that they're different toolkits, but that they often have drastically different theming and UX. Uniformity through common theming/UX APIs would be beneficial.
"It" can be any distro. GNU/Linux distros aren't a single entity, and they never will settle on a common interface---that's a good thing. Larger distros like Ubuntu will, but if you're going to adopt this perspective, you'll need to start thinking about the individual distributions and companies/communities behind them rather than "the" GNU/Linux desktop.