I think the problem with over-use of "awesome" is not so much its use for less substantial things, but its use as a generic positive adjective. Awesome has a meaning - it means "inspiring awe". I've seen awesome skateboard tricks, they inspired in me a sense of awe at the skill and athletic ability of the skateboarder. Awesomeness of course is defined in terms of a person's reaction, so it's a subjective thing. I have no problem with people who have awe instilled in them by things I don't find awesome. But some people use 'awesome' to mean 'really good'. As in "I know an awesome mexican restaurant where we can have lunch". Here the speaker isn't talking about awe at all, and that is what dilutes the word.

Same thing with "incredible" and "unbelievable", with "fantastic" and "fabulous". These words don't just mean "really good", they carry specific meanings for why the thing they describe is good. Describing a scientific result as "incredible" means it's bad science, since the result cannot be believed. Describing a business plan as "fantastic" means it's terrible, since it's far removed from reality, a fantasy.