I'm thinking you're not a guitar player.
Hop on Beatles tabs (http://www.ultimate-guitar.com/tabs/beatles_tabs.htm) and check out some of the subtle complexity of their pre-Revolver work. Check out any of the material on "Anthology" to hear what went on in the studio even before Revolver. Everything was not all "Love Me Do" three-chord stuff like you claim . . . not by a long shot.
“{Subtle complexity” = same junk over and over. They wrote 3 dozen love songs that are basically the same. Then they started doing drugs and at least got kind of interesting. But by then it was too late.