Re: 1) Choice is generally a good thing.
Again I say, how come choice is bad here. Actually, people back in 8 bit days coped with many different BASIC's and low level O/S's. Even the de facto standard CP/M came in many variants and people coped.
Plus, people cope with choices of car - manual vs automatic, two wheel or four wheel drive, electric, petrol or diesel, et al, not to mention the horror of choice for breakfast or toothpaste flavour.
In relation to system settings, as I stated, I do not know what half the settings in KDE do. So I ignore them. I worry about the ones I do know or I need to know. There were masses of config option in Windows for ages (I grant, now reduced as Microsoft have scaled back configuration options) and users coped by... ignoring control panel.
Personally, I am grateful for the fact that if I need to adjust something in KDE I can look up the required system setting online and go into, shock surprise, system settings and click something.
If I look up how to change a setting in just about another other UI in Linux instructions come up on the line you have altered in the buried text file.
I will grant that because people seem oh so overwhelmed by KDE' settings and cannot just ignore things as they used to up to and including Windows XP, (then with Vista Microsoft started hacking options out) I think KDE should have in each category basic settings and 'advanced' to partly hide the mass of options that seem oh so confusing for users... but when the choice is having settings available in the core UI and selectable by GUI as opposed to not being able to configure options save by:
sudo nano ~/.config/share/whatever/thiny ... type gibberish, save.
I am the kind of crazy that says, "I prefer point and click."
Annnndddd... there are defaults. People like defaults. Use the defaults. Point and click if you really need to change something. That just seems sense to me! How come the idea of modifying what amounts to .ini files to configure your system suddenly became forward looking?
Annnnndddd (again,) when I do show KDE off to potential converts - and I have go some here in Indonesia - it sure impresses when I show how KDE can be tailored as they see fit.
In fact, KDE's configuration has saved me a lot of training time. When I do get a convert, when they are getting to grips with the system I am always asked; "In Windows I used to be able to X this way... Can Linux...?"
"Yes." I reply and flick the switch.
So rather than having to retrain one time Windows or Mac users, I just configure KDE to work they way they are used to. Far less training and support.
With KDE the answer is always "Yes" and it can be switched via the GUI. Not so with any other UI.
This is not even an issue of choice, it's just usability and access.
Editing text file vs point and click. Seems a no brainer to me.