To quote H.L. Menken, “Explanations exist; they have existed for all time; there is always a well-known solution to every human problem — neat, plausible, and wrong.” Of course, he was talking about explaining the source of "inspiration" (the essay it's from is titled The Divine Afflatus), but the point stands. Your explanation has all the wonderful qualities it needs except the most critical of them all: whether it would ever actually work in the real world.
The fact of the matter is, it simply won't. Players-in-general won't accept randomly-generated spell picks; I don't even believe GMs in general would accept such a path. I sincerely doubt either side would even accept GM-curated spell picks, but that one, I will admit, I am not 100% certain of.