On most teams, I would probably agree with your argument that bigger guards are better. There are advantages of being taller. But you may have defeated your own argument by posting the measurements of our guards from the past few years. Other than Michael Redd (who didn't play much defense until his last year), our best all-round guards have been Stockman, Darby, Dials (all 6'1"), and Scoonie (5'11"). Plus we have the probable Ohio Mr. Basketball this year and a true scoring machine Butler (6'2") coming in next year. Granted, Stockman and Dials have yet to make their mark as really good
OSU guards, but I'm willing to bet that they will.
It's easy to notice the extremely talented taller guards, but I'm sure that there is a lot of tall guards sitting on the bench all over the country, also.