I was saying the same thing. Then, I had a light turn on. Marco Rubio will bring Florida to Romney from where he is. He won't be distracted from that task campaigning around the nation. This will be a huge advantage for Romney with Rubio speaking to the Latino community in their own language.
Rubio has had brushes with scandal. One of his friends David Rivera Congressman form South Florida is under investigation and very seriously so for living off a party credit card for ten years. Rubio charged $100,000 on that party credit card and $16,000 he spent for personal items. But had repaid American Express. If he were chosen he would have had to list each item and something that would not be good for the media and Obama to be harping on. There was also another scandal close to Rubio that could have come back to bite him politically even though nothing really was shown that he had done anything wrong. I think you will find that Romney did not want to invite the scrutiny about this stuff into the campaign.