Page 104 of the Winston effect.
"Initially, the mask design was a mechanical interpretation of the creature's face. To avoid giving away the look of the creature too early in the film, SWS later changed the mask design to a simpler, more 'tribal' look."
When I first read it I pretty much thought SWS just meant Stan, and I still think he most likely suggested the other look. (Any artists out there? How many times you painted/sculpted/made something, looked at it and said...."Nah I don't like this look anymore.")
But yeah, it wouldn't surprise me if it were several saying "Lets use something that doesn't hint the surprise."