If the movie is actually better than people expected, maybe the flopping is just bad advertising -- I know Toei tried to really drum up interest in the Space Sheriffs around its release with things like the comic and the 30 Year Memorial, but the ads for the actual movie? Really didn't make it look that great. And to make it worse, those two Go-busters episodes were some of the worst episodes of Go-busters, period, and maybe not the best first impression for the new take...
:shrug: