Indiana Gov. Mitch Daniels (R) gave a perfectly serviceable speech last night. It was a bit dull, maybe, but it wasn’t a wrenching exercise in self-humiliation. Which is to say, by the standards of post-SOTU responses, it was a stunning, historic success. But it was also a reminder of the difficulties Daniels, a fantasy-draft presidential pick for many Republicans, would face if he entered the campaign.