I personally wouldn't characterize Asimov's writing as anything near awful. It's simple, yes-- but only enough to bring a layman sensibility to the most esoteric and abstract of concepts.
This isn't a criticism he'd be surprised by. He said so himself, several times, in some of the books I have. Romance in particular was a weak point of the entire genre during his era, and he admits it's because they were all pretty stereotypical nerds.
Fortunately, that's not why we were reading his books.