One of the biographers of the Beatles pointed out that Paul was a total whiz at cranking out tunes and fluffy lyrics, and that John was sharp and odd and wandered off into the intellectual swamps of wierd image and bad pun pretty easily.
It was that combo; Paul's lovely tunes and light, and John's cranky edge driven art -- that together made those amazing songs.
Whoever it was that wrote the bio I'm remembering said that Paul wrote both great tunes and total crap really easily, and couldn't tell them apart himself. It took the other band members to sift it.
Blessings,
Barbara