I'll be using Super Sentai as my example here, but it and Kamen Rider are taking a tumble for the worst. My biggest example of this is Tokumei Sentai Go-Busters, the most recently completed Sentai series. This post isn't here to review Go-Busters, but I think what it represents will definitely get across my argument well. The biggest problem I had with Go-Busters is not only that its characters were very bland and one-note and really didn't have any big defining character arcs beyond "my parents are dead", but that it relied too much on it's action and comedy to really carry the story, and even those elements were very very VERY lackluster in my opinion. Enter (aka Pinocchio if you have seen the show) is also a really big pushover and halfway through the series COMPLETELY changes his goals and priorities for no reason other than that is what the writers and producers want him to do.
After doing a lot of thinking about why this is happening to Go-Busters (and to the current Sentai, Kyoryuger as well but not to the same extent), and then it hit me as the priorities of Enter changed in Go-Busters, so did the priorities of Toei Co., the studio that creates these shows. During the halfway point of Go-Busters, the ratings dropped significantly to the point that Go-Busters ended the main storyline by episode 30 and created a brand-new one to fill out the other 20 episodes of space: The tone was different, the characters were different, and everything had changed from the first half: It has turned from boring and somewhat tolerable to annoying and mind-numbingly awful, and that was when the downward spiral truly started.
With this, my conclusion is more or less this: Because of the ratings drop from Go-Busters in the middle of its run, Toei is probably going in this direction in order to get the ratings back to normal so they can go along with the franchise. From what I've heard, Kyoryuger is pretty popular in Japan right now, all I hope is that they go in a different and more character-driven direction for Tokkyuger, and with the Shinkenger team on board to do Tokkyuger, that may seem like a good possibility. Let's just keep our hopes up for now. =)