There's a message that the poll is trying to send. It's that Americans feel most comfortable identifying themselves with those who have been most often described by the press as "moderates" (like Huntsman and Romney), who come across in a relatively non-confrontational way and largely avoid vilifying their opponents or indulging in "extreme" rhetoric (unlike Obama and Bachmann). (Paul's support shows there is a significant and vocal "strange bedfellows" contingent of lefties who want to withdraw from the world and libertarians who want a much smaller federal government).
The first point worth making about the poll is that -- however much true believers on the left and right would like to think that the electorate is "secretly" with them -- most Americans seem to see themselves as right-leaning moderates, for better or worse.
What's more, it suggests that voters are less likely to gravitate toward the general-election candidate whose rhetoric projects a threatening "extremism" (in moderate eyes) in his/her views.
Optimally, we would have a candidate like Ronald Reagan -- a man with the capacity to communicate a strong conservative message in a way that invites agreement, not alienation. But every election doesn't have a Reagan, and it's not always a betrayal of principle to embrace a person with views that regular Americans profess to embrace, especially when there's a solid argument that he may well be more solid than rock-ribbed conservatives believe.