With the understanding that every candidate (yes, including the Messiah) is bad for the country in some way . . .
A policy of letting into the country anyone who wants in would result in a collapse of the country due to exponentially expanding demand on social services. A policy of letting into the country anyone who wants in and ending social services might or might not result in a collapse of the country, but would certainly turn it into a third world-level country full of desperately poor people.
A self-regulating free market would be an economic wonder, but would have incredible booms and busts. Most of us are not willing to trade the certainty of more recessions (if not depressions) for the promise of greater societal wealth. Also, a self-regulating free market coupled with ending government handouts would inevitably lead to segregation of society into the very wealthy and the very poor. This would either lead to a Marxist revolution or to a change in enfranchisement to dis-empower the poor - which would lead either to a Marxist revolution or to us being a third world-level country. None of that is an acceptable trade-off for increased societal wealth.
I don't think you CAN set aside the racist newsletters. I don't think Paul is in any way a racist, but whether motivated by profit or personal relationships he tolerated these newsletters and even attempted to defend them. That's a serious lack of good judgement, and judgment that might be overlooked in a Congressman can be catastrophic in a President. It's not really comparable to Obama and Wright, because of degree of racism, degree of connections (tacit acceptance by church membership is much weaker than something published in one's name), and potential effect - racism of the majority against a minority can potentially carry much more power than can racism of a minority against the majority.
I like some things Paul says/stands for, and I'd like to see the federal government cut back. I think in general, government governs best that is closest to those governed. But I'm much closer to Romney than to Paul in my idea of how (and how much) the federal government should be cut.