"....worrying too much about petty stuff like how an OS looks or feel...."
Excuse me, but, no. The 'look and feel' were mostly developed at Xerox PARC and continued at DRI with GEM. The windowing GUI was entirely fact-based upon years of careful research done at universities around the country, from basic psychology/human factors outward, and often using grants from DoD and DoE (AEC, I think, at the time); it started with the fundamentals of perception, of visual- cortex shape and color acquisition (icon development), of hand-eye coordination (mouse, light-pen, etc.; menu style and list length, conceptual grouping), control - click, scroll, drag, and the whole shebang analyzed to a fair-thee-well for real, live, measured usability, all feeding into a synthesis that gave us the desktop metaphor with the then-standard classes of icons (file cabinets, etc.) in the computer space.
Much of the original research was done in search of more effective display and control presentations for operators at nuclear power plants and for pilots, as some examples (and along the way the "seven digits for seven steps can be remembered" was validated). For a while Navy and Air Force were largest customers - split roughly twixt HUD/glass cockpit and engineering (nuke ops and missile control; the HUD for sensor integration, target acquisition and fire control for Abrams came out of this as well.) [I don't know how much of the background on all this is still out there, I haven't looked for any of it in almost fifteen years.] All told, nigh twenty years of various pieces of research from myriad sources coalesced to give us, among other things, a basic useful way of handling user-facing chores at the computer.
Current GUI - excuse me, UX design - is willy-nilly throwing much of this hard-won knowledge and fact-based, carefully-crafted interface design parameter set overboard based on.... well, I really don't know what it's based on, but it's not done for greater ease of use by the end user.
Look and feel is precisely the issue for those who spend the workaday in front of a computer working with it. Do whatever it is that needs doing under the hood; the focus ought always be the easiest and most pleasantly effective experience by the person using the software on the machine - and this includes being able to readily and comfortably see and use those parts of the OS they interface - larger window borders for easier re-sizing, scalable fonts, easily-apprehended icons, what have you, for just the simpler elements to start with.
I've watched for forty years and more the widening disconnect between those who spec, design, and build stuff and those who have to use the crap that's churned out - from the location of a drain plug in an oil pan to menu selection of a popular word mangling program.
If somebody is gonna design something new and useful and good, go out in the world and use what's already there, until your knuckles are bloody or you've got eyestrain - then go make better. Please do not gift me with the aftermath of what you pull out of your nethermost because "oooh, shiny."