Maybe I shouldn't have included the terrible Mystery Tour and Yellow Sub albums... nobody's going to vote for them anyway and they're screwing up the graph.
I never saw Ringo [or drumming in general] as an integral part of Beatles music-making. George Martin's piano has a far bigger part to play in most of their songs. Yes, if you wanted to be condescending then you could say that made them a "childrens' sing-along band", and songs like Yellow Submarine, When I'm Sixty-Four, etc would certainly partially justify that conclusion. But you don't count Hey Jude, Helter Skelter, While My Guitar Gently Weeps, and A Day In The Life as rock icons of the era?
For all their cool rocker image the Beatles were never a hard-rock band and stunts like Mick Jagger playing concerts naked would have been unimaginable coming from them, so it's really unfair to judge them based on a persona that they just didn't have. I agree that when they stretched beyond their normal styles [Glass Onion, Yer Blues, Sgt. Pepper, Tomorrow Never Knows] they generally failed [Magical Mystery Tour, for instance, was a flop, and if not for the imagination of the lyrics Sgt Pepper would have flopped too]. And if you listen to their pre-drugs works, they uniformly suck. So maybe they WERE over-rated. But still you can't deny that between Help! and Abbey Road they wrote some pretty kicking songs.