That title may seem a little provocative, but sometimes, that's the feeling I get when I watch some sentai series, who really shift the focus from that stock main storyline.
It's especially true in sentai series penned by Naruhisa Arakawa.
In Abaranger, the Evolian invasion pretty much takes the backseat, since the main conflicts in the show are the Asuka/Jeanne and the Ryouga/ Mikoto ones, and in both cases, the true evil comes from within the characters more than a true evil force (Asuka being lured by the power of the evil armor, and letting himself be possessed by it; Mahoro becoming evil, after having been raped, and as a result, wanting revenge against the one who should have protected against that but didn't; more than Dezumozorya, both characters have first to get over their own mistakes and their dreadful consequences to survive; they had to win first against themselves before winning against the enemy ; Mikoto was a man who felt he didn't have any real purpose in his life, so he became obsessed with having excitement, even if it means dying in the process ; and how can you care about the lives of others, if you don't even care for your own life? That's why Ryoga, who believes in others, wanted so much to save Mikoto: because he wanted him to care about his own life, because it was the only way for him to be able to care about others and stop playing sick games. It's interesting to notice that Mikoto "turned good" once he's found a purpose, and a reason to live). The other Evolian were pretty much in the background, and Lije began to get development once she's been involved with Abarekiller.
Dekaranger: Deka is a show which had only one main villain, the Agent Abrella; and unlike most regular villains, he wasn't the leader of the Alienizers, but rather their dealer. As such, Dekaranger was dealing with the daily life of a special police group, rather than a plot about saving Earth from evil, since they fought against evil as an everyday job. The show was mostly parodying police stock plots, with the Alienizers being colorful criminals.
Gokaiger was the tribute series, who was more caring about being an homage of the sentai franchise than anything else; despite having a traditional enemy group (the Zangyack invaders) they were pretty much underused, and kept in the background.
It can be noticed that Arakawa isn't the only main writer who want sentai series to go well beyond the "colored heroes vs evil" plot ; in her most personal series, Kobayashi tried it as well; it's especially obvious in Timeranger, as I've described in a previous post; http://tokuwarriors.blogspot.fr/2013/01/timeranger-very-atypical-plot.html ; and I think that the reason Shinkenger suffered from "plot stalling" is because Kobayashi cared more about describing the relationship between a lord and his servants, and what it means to have people putting their lives at risk for you (and the Kagemusha plot made that theme even more powerful, since Takeru knew he wasn't the one he pretended to be, even if he had to do that deception for the greater good) than the actual conflict itself.