This is about GUI appearance and ergonomy. I'll concentrate at XFCE, as I consider GNOME3's UI a lost cause, thus I'd find it hard to bring constructive arguments there.
I also hate with a passion so-called "UX designers". Those are folks who created Windows 8's Metro tiles, lightgray-on-white "Material Design" flat unmarked controls, and so on. They work from a Mac while not having to actually use what they produce. For example: * our XFCE's layout has a thinnish bar with actually useful controls (menu button, window list, desktop list, clock, systray, logout) at the top... plus a tall redundant "OSX dock" that takes a lot of screen real estate. It's too much even on 4:3 aspect ratio, and on currently prevailing 16:9 any loss to vertical space is bad. Most code, web pages, human images, etc, benefit from a portrait rather than landscape layout... => Can't we move two useful pieces from the dock to the top bar? * the default theme has a thin disappearing poorly marked scroller. This is nasty with a bad touchpad (laptops), high-resolution small screen (PDAs). * people tend to use computers with only limited lighting. The hacklab I'm in right now has mostly covered windows (and even some artificial light from the above!); at work opening window blinds too much can result in you getting murdered; I for one prefer to hack after midnight rather than at insane times like morning, etc. And this is not just hackers like us -- even Windows and Mac brag about "night mode", random websites have this as well, etc. On the other hand, if we install some themes by default they have at most lightish grey background. I packaged dark{cold,mint}-gtk-theme with real black, perhaps there are better ones? => Let's install by default a black theme, perhaps even enable it by default? * the default icon theme is fugly => Default to eg. faenza? * default font is ugly and poorly hinted -- the latter is especially jarring on a low-resolution screen I'm at right now, the former still applies to one's proper battlestation at home/work. Tarzeau recently had some interesting rants, but even Quicksand that recently got added (during hard freeze...) to desktop-base is pretty nice. Or, if you want something more conventional, Clear Sans (Intel Clear). Or, Inter. Or... => Actually configure a good font by default. Quicksand looks fine. * likewise, default monospace font. My personal preference (Mononoki) hasn't been made to build from source yet (b-deps are available now, but it's still in contrib), my other preference is not packageable; there's a bunch of good monospace fonts available for choice but _programming_ font is an especially contentious issue. => Default to anything reasonable -- ie, not Dejavu. Even Comic Shanns is better... * CSD is still a thing. No, your special program shouldn't get to ignore system theme, put controls in wrong order, miss some controls, not respond to minimize/etc if it's currently busy, etc. Consistency not one-off designs. => Install gtk3-nocsd by default in all desktop tasks but Gnome. It's not perfect but it helps. * Likewise, GTK vs QT themes. => If default desktop at install time was not KDE, make QT obey GTK theme? In general: could we please do something to appearance beyond choosing a wallpaper once a release? I'm a code hacker not a theme maker, so I see this only once it gets in my way -- but text readability does matter. (Discussing before filing bugs.) Meow! -- ⢀⣴⠾⠻⢶⣦⠀ ⣾⠁⢰⠒⠀⣿⡁ Imagine there are bandits in your house, your kid is bleeding out, ⢿⡄⠘⠷⠚⠋⠀ the house is on fire, and seven big-ass trumpets are playing in the ⠈⠳⣄⠀⠀⠀⠀ sky. Your cat demands food. The priority should be obvious...