I care about a Wonderlic for a QB to a certain extent, but really only as a basic measure. If they're 25 or more, I know they'll have a functional understanding of things. If they score a 10, they're going to have a much harder time learning the playbook.
Of course, some guys just aren't book smart in math or proficient in the english language but can read a defense like a Morgan Freeman narration; that's why interviews and film sessions are so important.