^Of course, the '90s was definitely a resurgence. I mean, when Toho ended the Heisei series to make way for GINO they immediately made Mothra movies! It was a solid time of at least one kaiju movie every year for... 17 years? From Biollante to Gamera the Brave.
Maybe I should qualify that it's the best boom time for American fans? We have Legendary making a shared continuity of films around Godzilla and King Kong and producing a sequel to the Hollywood Tokusatsu film Pacific Rim, and it seems interest has in the genre has really risen here: Godzilla Resurgence and the new Gamera film will of course be intended mainly for Japanese audiences, but there's still a lot of interest in them from America and the studios are throwing bones to American/International fans (showing off the Gamera promo film at an American convention, making an official English title and logo for Resurgence very early). Tsuburaya is straight-up simulcasting their Ultraman shows! In contrast, a lot of the Heisei and Millennium series was largely unknown to the American nerd population of the time.
Also, when we're thinking of eras we have to remember that in the '70s the Godzilla films were a part of a kids film festival not intended for general audiences, so even though still running for most people in Japan it was as if the series had already gone away.