I guess he must only listen to pop music. There isn't an awful lot of classical on DVD, at least not that I've ever found. Certainly you couldn't build a collection of DVDs that would encompass the basic repoirtory.
Naturally, good luck playing them in the car, tho there are car DVD decks, I guess.
The sound quality of DVD-V certainly isn't up there with CD, either. Nor would you be able to find all the stuff you'd want, unless again you are only into new pop music.