For some, Godzilla is a by-product of nuclear fallout in Japan that was a sort of reminder of the destructive effects of such a nuclear weapon. For others, especially Americans, Godzilla is simply a giant monster, often battling other monsters while simultaneously making a mess of the city it inhabits. The differences in interpretation here are the result of this Japanese character being marketed to US audiences. Apparently, we're just too dense to read the underlying messages here so Hollywood just turned him into a destructive monster without all that messy subcontext about war and weapons of mass destruction.
Now though, it seems like the true Godzilla meanings are making their way to American audiences at least in the latest incarnation of the film franchise.