A part of me thinks Linkara loves Power Rangers so much because it's so simple and it never challenges you.
Linkara liked to pretend with Lightbringer and his objectivist days that he had some kind of philosophical stance about good and evil, but in reality, he is all about cartoonish villains that want to take over the world and goody-good heroes. And he seems unable to comprehend anything more complex than "Villain wants to destroy the universe and that's bad."
Don't get me wrong, I'm not saying Power Ranger isn't deserving of Nostalgia or that it's bad, and maybe it does have some hidden gems there inspired by Super Sentai (The Japanese tend to be edgier with kids). But, overall, it's really as simple as it gets.
It knows it's a show for teenagers and it never tries to be anything else. I guess it's not wrong he still like the franchise, even after everyone has just moved on, but he really should've matured to more complex things by now.