Though I would understand how some might not find it appealing (it was a notch too brodude for me), I don't see how it is incomprehensible. Giant monsters vs. giant robots. Is it really that hard to understand?
King Kong and Beast from 20,000 Fathoms preceded Godzilla. Though giant robots weren't as popular in Western culture as in Japan, they do exist.
I only saw one trailer, but IMO bad editing and choice of shots did not give the action the sense of scale it should have. A giant robot is cool, sure, but a close up of part of a giant robot does not give you the same dynamics. It was a shitty trailer in that it didn't communicate well to the larger audience. Monster movies used to be popular 50 years ago, sure, but they were still a niche market.
Are you seriously comparing it to King Kong, or the conditions to how movies were made and marketed in back then? I can't take you seriously, I'm afraid. This isn't 1933 and movies are promoted quite differently today, to a different audience, under different viewing conditions. No one told people they needed to "turn off their brains" to enjoy a movie, for starters.