You're right, it sounds great--but it's darned hard for the average singer to nail it. In any case, I'd still consider your example to be an exception to the general rule, while the augmented second is used so often that I have to believe the author meant something other than what he actually said. (To be excruciatingly precise thought, augmented seconds are not used nearly as often as minor thirds, which are sonically identical, even though they're musicographically different.)

Actually, I'd say the beginning of The Simpsons' theme is the most famous example of an augmented fourth nowadays.