Gotta disagree with you there. Politely, of course, since this isn't a debate thread. As a kid and even still today I think The Far Side is extremely witty. It isn't really my type of wit, although I do find it humorous enough to smile at, but intelligence is certainly not a trait it lacks. The simplicity you cite may even be a testament to that; one need not necessarily be complicated and elaborate to achieve intelligence...especially in some of the arts. Gary Larson's ability to boil down meaningful ideas into a simplistic, intuitive presentation is quite remarkable!
The ability is true enough I suppose, but I don't find it unique to Larson. It's a rather common attribute to come by in regular everyday comics. I will admit, there are some excellent Far Sides that make me laugh for a long time, but most are just so obvious that they really aren't very funny...at least not to me.
I suppose I described it wrong. It's not "simple" so much as "obvious." Or...maybe it's both? *shrug* I don't even know anymore, haha.
I just agree that Calvin & Hobbies is brilliant.