I think the word godzilla was used to describle r32 because it was a monster of a car, because of the massive power capabilties and could eat up corners for breakfast. its a metaphor!!
The way I see it is the r32 gtr can be beaten by an r33 gtr, and an r34 gtr can beat them both. Therefore they all deserve the right to be named GODZILLA!!!
So there I've answered the question with some logic.