Call me crazy, but shouldn't the goal of hiring op-ed columnists simply to be find great writers (preferably local for papers that aren't national like the Post or the New York Times) who make you think. I'm pretty sure that casting that wide net would pull in conservatives as well as liberals. The New York Times, in fact, with a false start or two, has done a fairly good job in getting David Brooks (whose conservative credentials are under review after his flirtation with Obama) and now Ross Douthat, who writes some weird stuff on sex but has been fairly readable on other topics; certainly you'll learn at least more from a typical Brooks column than from Maureen Dowd channeling the Beltway zeitgeist with her strained analogies, and have you noticed that some of the most pointed criticism of Obama has come from having a true liberal around in Paul Krugman? Here in Philly, Michael Smerconish -- who I profoundly disagree with on torture and a few other issues -- is at least a lifelong local guy who surprises and can be provocative -- but hey, it's a lot easier and less hassle (and cheaper, frankly) to get Linda Chavez to recycle whatever the oil-industry funded think tanks are gushing out this week.
But like I said, it's just a lot easier for editors and publishers to mindlessly try to big yellow line in the middle of the old worn-down highway than to search for a new route -- even when there's a 16-ton Mack truck barreling down the other direction.