I'm a drummer so you'll have to excuse me on this, but most of my friends are guitar players and most of them agree that the bass is a harder instrument to play (well that is). I cant argue this, but that seems to be the consenses. I've heard George absolutely butcher some solos (Slow Down, What Goes On, etc,,) to the point where its embarrasing. I dont like a lot of his early Beatle guitar playing. Theres a ton thats sloppy. He's not gods gift to the guitar that your making him out ot be.
I agree with TK on this. None of the Beatles, even Paul or George, were technically virtuosos. Just listen to Joe Pass or Jaco Pastorius to see what someone could do with guitar and bass. The Beatles were "vibers" as an earlier poster well put it. They had this great connective musical tissue binding them. That's why I think so much of their solo work suffers in comparison. At times the "vibe" can be hard to find.
Who would you rather have noodling around on your song: John Lennon with his idiosyncratic skiffle-licks who you've been playing with since your teens or some session ace who knows the names of all the chords, can write charts and play circles around you if he felt like it?
Ringo (with his touring band) did the best of coming up with fellow vibers (like Levon and Rick Danko and Steve Cropper and Duck Dunn--vibers all). Hell, there's a great live version I've heard of "Boys" with Jerry Lee Lewis (King of the Vibe) playing a "killer" piano solo. (At least I think it's JLL).
In a way, becoming a studio band may have been what "killed" the Beatles--since they weren't really studio musicians by temperament or skill (and had to do countless takes that pro's would have gotten down in less than an hour--i.e., see the "Wrecking Crew.")