_Maybe_ you don't need that much CS per se (debateable, but an argument can be made); however you do need a lot of math coursework.
Also, it's far easier to grasp the basics of AI from a course than to reconstruct "basic body of knowledge" just from reading arxiv. As a matter of practical considerations, I just don't believe anybody can become an expert by reading only the research, without going first through the basic training. It's too damned difficult, too much work (and pointless, too - people did that work for you already and built great courses with the summaries, why not take advantage of that?
Also, it's far easier to grasp the basics of AI from a course than to reconstruct "basic body of knowledge" just from reading arxiv. As a matter of practical considerations, I just don't believe anybody can become an expert by reading only the research, without going first through the basic training. It's too damned difficult, too much work (and pointless, too - people did that work for you already and built great courses with the summaries, why not take advantage of that?