[Matrixbeast]

I wouldn't say Super Sentai had a dork age.
Go-Busters may not have been the most popular, but it wasn't a massive letdown, and Go-Buster Ace sold like mad.
While Kyoryuger was pretty decisive for the older fans, I'm pretty certain it was a hit with the target demographic.
For ToQger, it's about as 50/50 as Kyoryuger, but from what I've heard, once you got past all the "IMAGINATION!" stuff, it was pretty fun (Haven't seen it, can't confirm)
Ninninger is bad.
Zyuohger is good c:
As for Kyuragner, I'm hearing people vouching for it that it gets better and Lucky actually grows. I don't believe them, but if they say so, then okay.

A bad season or two in a row isn't that rare for Sentai, and they typically tend to pick things up when they notice things are going south to shake things up some. So I wouldn't say Sentai has had a "Dork age."