Actually, Ryan wanted to take a broader approach, but Romney wouldn’t let him. Ryan is a big social issues person, and even wanted to go and speak in black areas about initiative, family, etc. But just about the day after he became the VP candidate, Romney or Romney’s advisors shut him down.
Romney wanted to run just on the economy, with no social issues (since Romney is a liberal on all of them), and he made Ryan stick to that. But contrary to popular opinion, the economy wasn’t really the issue: vision was, and Romney didn’t have it. Obama didn’t have a vision, but since Romney didn’t have one either, he presented no challenge and people decided to stay with what they knew. And, of course, large numbers of Obama voters voted for melanin, a truly puzzling political qualification that no argument would have been effective against.
Rubio is excellent, but Romney wouldn’t have let him speak either. Romney and his advisors had a truly myopic vision, focused on tiny economic questions, which they thought would be safe and keep them out of “social issues.” But in doing so, they seriously underestimated the American population, which was looking for a lot more than the new boss same as the old boss.
Ryan was a huge disappointment...unlike Palin in 2008, he simply did not have the courage to ignore them and "go rogue."