Understandable that the creator wouldn't want fetishes in that he doesn't particularly care for, whatever the reason. I mean, they are his games.
I know this is somewhat off-topic, but if you are looking for a game with weight gain mechanics, then look up Tainted Elysium. Weight isn't really what I am into, but the game looks pretty good. Unfortunately it is incredibly unfinished at the moment, with sparse content. It might tickle some fancies as it is though.
I'm aware of that game and plan on playing it. I'm on another forum called WeightGaming.com.
Basically just people with fat fetishes trying to find games that give them what they want.
Regardless of fetish though I think it'd be more fair to open up a new avenue of character customization in a game that prides itself on its in-depth body system.
The game already allows you to have absurdly large tits, asses, and hips so why not? Maybe work it into the survival system?
Really fatness is already in the game but isn't described very well and is really ambiguous on how large the player is.
There's even a secret binging scene you can find by bringing Shouldra to the Tel'Adre bakery.
More than that there's another gorging scene if you complete a quest for the Bakery and buy the Giant Cupcake.
The main reason WeightGaming exists is the lack of games that allow fatness. It'd make a lot of people happy.
CoC appeals to a lot of fetishes already so why not appeal to one of the much tamer ones?