I'm not trying to convince you to like OSX, but just to attempt to give an explanation:
Compared to Dolphin, I find Finder far too limited, especially the inability to show hidden files. I've got no idea why there is no such menu toggle built into it. What are Apple afraid of? This is especially annoying when I have to look for .m2 and .git files. Sure, I can use the command line, but it's not as intuitive.
As someone who provides support for general users, I think Apple has handled this reasonably well. There are a lot of hidden files that a lot of people would find confusing. There are .DS_Store files and .Trash folders, along with the /etc directory in the root. If they had a little button on the Finder to "show hidden files", I have no doubt that there would be a lot of users who would hit it, see all the "Junk" in places they didn't like, and try to delete it.
Apple provides a option to show all files that can easily be changed from the command line. If you have trouble making this change, then you're not someone who should see those files. Seems reasonable to me.
The mouse scrolling was odd; the whole concept of "accelerating" while operating the wheel doesn't feel as natural as moving 2-3 lines with each movement. I had to download an app to get it the way I wanted (or, the same as it works in Windows and KDE).
Seems like a preference issue. To each his own, I guess. I thought you were going to complain about the "natural scrolling", which is something I'd have a lot more sympathy for, but which is also an option that can easily be changed.
It took me ages to realise that Command-Tab cycles through open applications, but not the windows. I found several windows all hidden behind one another that had been there for days, because OS X's window manager didn't present them to me. Apparently, I have to use Expose or something like that to see all of them.
Again, seems like a bit of an issue of preference. Ultimately, Apple's logical breakdown of running processes is much more aimed at whole applications rather than windows. Notice that each application has one button on the dock, regardless of how many windows you have open. Notice that you can often close all the windows of an application without closing the application. Notice that you can (depending on some thing) close the application without actually closing the windows, i.e. the application closes and the windows disappear, but when you reopen the application, the windows are all there where you left them.
Their approach is sensible, and it doesn't seem to be obviously wrong, but I can understand why you'd want it the other way.
Oddly, most things on Mac are Command+. However, on the command line, Ctrl+C is still used to break a program.
In my opinion, it's actually fairly nice that way. You can use Command+C to paste text into a terminal window, and Ctrl+C to break the current program. Less confusing than windows, where the short-cut's effect will change depending on context. In fact, Microsoft has been advertising the ability to use Ctrl-V to paste into a command line in Windows 10. Apparently, it's one of Windows 10's biggest features.
My Mac has been set up to be case insensitive. LS, GrEp, cAT, TAIl all behave as if they had been typed lowercase.
Yeah, this is... well... it's a bit unfortunate because it can cause some confusion. It's an issue with their file system (HFS+), which has been made semi-case-sensitive. For example, you can do "mkdir tEsT\ dIrEcToRy" and you'll get a directory called "tEsT dIrEcToRy", maintaining the case that you types in. However, if you then type "rmdir 'Test Directory'" then it will delete it. Essentially, it's case-sensitive when writing but not case-sensitive when reading.
The reason for this, to a large extent, is lazy/bad developers. You can set the filesystem to be completely case-sensitive, and OSX will run fine. Apple's applications will run fine. Last time I did it, though, Adobe applications would crash constantly if they ran at all. Apparently Adobe had developed their applications without paying attention to the case of their library files. It's worth noting, also, that Windows seems to have the same problem. Also, this doesn't really keep things from working.
Pressing home and end take me to the top and bottom of the document, rather than the line I'm edit, making me have to do some finger gymnastics when I want to highlight an entire line I'm working on. That's probably just personal preference, though.
I think this was actually how things were done first (even on old Unix systems), and the Home/End buttons got re-purposed later to be the beginning/end of the line instead of the beginning/end of the document. Again, I'm not sure this is a matter of right and wrong, so much as a matter of what you're used to and what you prefer. Also, it's worth pointing out that Command+Right-Arrow will bring you to the end of a line, and Command+Left-Arrow will bring you to the beginning of the line. So you can still do that.
I can see if I were to switch to a Mac, I'd spend a lot of time downloading hacks and scripts to bring back the features I like to work with, and other scripts to do away with those that I don't.
My honest opinion is that doing so would be a bad idea, and largely a waste of time. Apple would release an update, and all your hacks and customizations would be broken. You'll be better off just getting used to the way things work instead of trying to tweak every last thing to work like KDE. It's largely not doing things wrong, but just doing things not the way you're used to.