There's nothing contradictory about Linux. No one praises it's GUI. They praise its customisability but that's as far as it goes
Oh, I do. I love the GUI. At least I love my GUI, centered around Openbox. It's the main reason I use Linux by choice instead of Windows or OS X. It's easy enough to get much the same command line on both of them, and with OS X it's basically already there, embedded in the dumbed-down OS X GUI. My GUI got like it is because I could customize it, so customisability is certainly part of the appeal. I have my own themes and I can move the themes and settings from one machine to another by copying a few text files. Openbox also gives me sloppy focus, multiple workspaces, keyboard control, and command line integration without much effort, and it's fast and runs on old hardware.
A lot of this can be done with Windows and OS X. All of it, technically, because you can install Openbox with an X server. And that's how I ended up working (even where I started using Openbox) but it's easier to install Linux and be done with it if you want a Linux GUI (like I do).
It's a shame Gnome was always reluctant to support other Window managers, and dropped them completely with Gnome3. It means the GUI I use is lacking a few features, like configuration screens for monitors and keyboard mappings. So if you want that you're back to Gnome or KDE or Unity. I assume somebody must praise them or they wouldn't have got to be the defaults.
Gnome2 was getting quite good, so it's possible MATE would do what I want. But I haven't tried it because, as a Linux user, I'm more interested in getting things done.