Well, first of all, there isn't much alliteration in Van Dyke Parks's lyrics. You're using the term as it was misused by Mike Love. Furthermore, I don't find Parks's lyrics to be vapid in any sense of the term. His use of puns, jokes, wordplay and his ability to conjure images with language show a fairly strong skill at writing, in the vein of Edgar Allan Poe. Kokomo's lyrics, on the other hand, could have been part of a jingle put together by a travel company. But, again, this hasn't much to do with Mike Love since he didn't really have much to do with those lyrics.
Here here. I always wondered if Mike meant "acid illiteration." Illiteration obviously isn't a word but it makes more sense to diss VDP&co by calling them illiterate than by accusing them of using a literary technique that actually isn't seen much in the lyrics.
If that is the case, big ironic lulz abound.