Before I get into responses, I think Shougo has basically nailed it for why Go-Busters is going over poorly in Japan. Everything I've heard about Japanese fan feedback on the show indicates that they think it's "dull" and "plain". Kids are probably tuning out because it bores them.
I think the show suffers from falling between the stools: it's not funny enough to be a show where comedy is a big draw, but it's not really serious enough to be something you watch for the drama. The only people really tuning in for it in Japan now are Sentai die-hards, and I feel basically the same thing is happening over here in the West, too.
I think Go-Busters was probably intended as a "first principles" show, maybe similar to W, that rejuvenated the franchise with a back-to-basics approach. A "first principles" show really only works if the creators have something to say about the franchise, though, and it's clear by now that Takebe and Kobayashi have no big statements about Sentai to make here.
That's a funny thought, since producer Takabe is seen as the mother of all pretty boys for Toei series.
And that view is
complete horseshit. The ikemen boom starts with Kuuga and Timeranger, shows Takebe didn't work on. When she did work on Rider, she was only an assistant producer until Kiva, and wouldn't have had any sort of final say over casting. All she really did with Kiva and OOO was imitate casting choices that had proven successful before.
The idea that Takebe originated pretty boy Rider casting comes from an awful puff piece that ran just before Go-Busters started, trying to make it seem like she was somehow responsible for Heisei Rider's success. So therefore, you should watch Go-Busters to see what she'd do with Sentai!! Except Go-Busters pretty much proves that Takebe can't innovate to save her life.
I really, really doubt she was going after "not so pretty people" this time.
Given how old Ryuuji is? I
seriously doubt it. Go-Busters just doesn't have an ikemen cast at all. I think Escape was added almost purely to get some sex appeal into the cast, though I think that move backfired.
I would say they were casting for acting or performing ability, except... the Go-Busters cast really isn't all that good? Or maybe they just don't have much to work with, I dunno.
This 'retooling' theory seems to have come from people presuming a new opening means the whole shows going to change.
Actually, it really got started when we found out we were getting a new opening, and then like a day later found out that the title of episode 30 was "Messiah, shutdown!!" It's also looking like Escape is getting written out, since they didn't bother to put her in the OP (nor did they bother to put in Messiah's new monster form).
Right now, all available information indicates that Messiah is simply not in the show anymore past episode 30, although apparently Metaroids still are. It seems like Messiah and Escape are getting written out and probably replaced with Enter serving as main villain in some form. That really, really, really doesn't seem like a plotline the show would've planned all along to me.
(Especially not for Escape, whose addition to the show was hyped up pretty heavily, for a villain.)
