On the specific topic of KAs they can be had for the same price as a lot of L-series engines. Its also way more powerful than and L-series youre going to find and thats in stock condition. I dont personally see leaving an L in my Dime, but I see the draw of KAs. Its not just a single answer. Its a combination of all those factors you listed. Price, power, attainability, EFI, ease of install... it all adds up to a good swap.
But youre correct in the fact that everyone seems to want to swap everything. Like 90% of new members (myself when I first signed up) have SR plans. Its ridiculous.