Romney knew that he was going to be pilloried and abused as a Social Darwinist already: it must have occurred to him, why run from it?
In Washington, you eventually learn not to worry about what people say about you, because your opponents will rationalize everything their way anyhow. If Romney had picked Portman, then they would have called Romney a coward who approves of Bush’s budget director. If he had picked Rubio, they would have said Romney caved to conventional wisdom. It’s just the way campaigns work: no matter what you do, you will be attacked.
One reasonable objection; however, might be that you want a guy like Ryan in the House, where he has risen by sheer merit to a leadership role. Reportedly, Ryan even turned down a job as OMB director for President Bush. But Ryan is already term-limited out of staying on as Budget Committee Chairman; would you put him on Appropriations? Ways and Means? What would you do with him? His effectiveness would be diminished in the supporting role which he must now take on.
Therefore, Ryan as Vice-President is a perfect match. He shares many good qualities with Romney, and compliments the few that he lacks. The job of an executive is to make decisions, and Romney has demonstrated a brilliant judgment. It took courage for Romney to pick Ryan, and there has been no better example of courage in Washington than the Budget Chairman.
And no one should question whether or not Ryan is qualified for the job. Put Ryan beside President Obama. One is a dorky numbers guy; one is an entertainer. One is all substance, one is all style. We will know in November which one we should choose, and we again will therefore know who we are.