This is just senseless hating IMO. What is wrong with KMail? KolourPaint? Konsole? Ktorrent? KSudoku? These are all straight forward and descriptive. Nobody bats an eye at "Gmail" but KMail makes people lose their shit apparently. Come on.
And of those that aren't plain and descriptive, most of them seem inoffensive. What makes Kate such a worse name for a text editor than "Vim", or "JOE"? What's so awful about a PDF reader called "Okular", when the competition is named named after southwestern construction materials and trapeze artists e.g Adobe Acrobat? At least 'Okular' suggests the program is for viewing something. Corporate brand can be as bizarre as the strangest KDE names, the only difference is what you're acclimatized to.
It's just a personal preference. I can't tell you why, but I just don't like how all of the programs start with K. I think it looks weird.
It also annoys me every time I try to search for the calculator by typing in "Calc", but nothing is found because I forgot I need to look for "KCalc"
I think at the very least, commonly used applications like "Calculator", "Console", "Mail" should just be called "Calculator", "Console", and "Mail". Not everything has to be branded. The mail application on Windows is called "Mail", the terminal is called "Terminal", etc. They don't call them "WinMail" or "WinTerminal" for a reason. They know most users would find that off putting
Better than gnome where every program has two names; one used in the documentation and . desktop file, and another used at the command-line and by the package manager