I think the biggest mistake there is using SI prefixes (such as kilo, mega, giga, tera) with bytes (or bits) to refer to the power of two near a power of ten in the first place. Had computer people had used other names for 1024 bytes and the like, this confusion between kibibytes and kilobytes could have been avoided. Computer people back then could have come up with a set of base·16 prefixes and used that for measuring data.
Maybe something like 65,536 bytes = 1,0000 (base 16) = 1 myri·byte; 4,294,967,296 bytes = 1,0000,0000 (base 16) = dyri·byte; and so on in groups of four hex digits instead of three decimal digits (16¹² = tryri·byte, 16¹⁶ = tesri·byte, etc). That's just one system I pulled out of my ass (based on the myriad, and using Greek numbers to count groups of digits), and surely one can come up with a better system.
Anyways, while it'd take me a while to recognize one kilobyte as 1000 bytes and not as 1024 bytes, I think it's better that ‘kilo’ always means 1000 times something in as many situations as possible.
For whatever it's worth, I use (up until fairly recently) KDE Plasma on Arch, and it's pretty much fine. There's some hiccups especially after a big update such as KDE Plasma 6, but it's a smooth ride so far.
If the KDE Plasma developers support an Arch-based distro of their own, and package stuff for this distro with care, I think it'd be a better experience, but I am guessing not by much compared to KDE Plasma on base Arch.