Forgive me but what 'franchise fatigue'?
That's easy in this case. What happened with the film from 2014 is that the casual, mainstream audiences were interested enough in checking it out since it had been 16 years since the previous big budget Godzilla movie. KOTM came out only 5 years after the 2014 film so as a result only the more hardcore dedicated fans of the monster genre bothered to go see it. In other words, KOTM came out too soon.
You definitely seem to be a hardcore fan based on what you've posted so far so you are thus in the minority when compared to the overall mainstream, casual audience. My ultimate point is that if you want a big budget movie to be successful at the box office, it HAS to appeal to audiences beyond the hardcore niche.
First I need to apologize if I came across as 'terse' ro rude.
But You ARE Right I am a fan of long standing. AND you're also right that the mainstream casual audience has no attraction to the film, much to my dismay; it's like Pacific Rim: Del Toro created the perfect love letter to the 'Tokusatsu' Genre he loved as a kid in D.F. and it was a great movie too. But the sadly it seems the US doesn't have a lot of Kaiju/Tokusatsu fans as opposed to Asia, so two rather well done films that were 'fan service' to the max didn't attract 'normals'. I did my best: my daughter & I saw the film 4 times: twice we dragged one of my daughter's friends to see it--at first they were kind of 'uninterested' but once the SHTF they loved it. The one person I could NOT convince to go was my wife--she simply didn't care...not even for "Fathers Day";
That being said,I should reserve my anger for the supposed 'fans' who whined and pouted about how the CGI generated film 'cut away' from the fights and they were going to withhold their $$ because it wasn't like the TOHO flicks were men in costumes bashed carboard and plaster cities right on camera--like those whiners couldn't understand the diff between well made CGI combined with Motion Capture rendered in a computer was HUGELY more expensive than suitmation.