Rand Paul clearly is seeking to move the GOP in a more libertarian direction. Most recently, he has called for changes to "cookie cutter conservatism," referencing a change in the party's position on drugs (for one example) as a way to attract more young people to the GOP (http://www.foxnews.com/on-air/fox-news-sunday-chris-wallace/2013/03/24/sen-rand-paul-top-congressional-issues-pivotal-moment-battle-over-gay-marriage#p//v/2250608088001).
In theory, libertarian principles often sound great, especially when you're young. After all, it sounds pretty good to announce that the government should just stay out of everbody's business.
The problem, however, is that it doesn't. And over the past several decades, America has done a poor job of reminding everyone that with rights come responsibilities, and with actions come consequences. So, for example, if everybody wants to legalize drugs, just keep in mind that, without fundamental reform of our social safety net first, taxpayers will end up subsidizing those who become unable to hold jobs because of addiction. Likewise, it's easy to insist that government get out of the "marriage business," but there's little prospect that doing so will mean that the government will also get out of the "business" of having to care for the offspring of unmarried parents (who truly are, too often, the victims of their parents' terrible decisions).
The Founders made it clear that they believed that the kind of Republic they were creating depended on high levels of civic virtue in order to survive. So are libertarians (and smart libertarian-Republicans like Senator Paul) ready to talk about the kinds of virtues necessary to support the freedoms they espouse? That's when I will start taking their proposals seriously, and as something more than simple pandering to various disgruntled groups and/or the young.
No, talking about things like "civic virtue" isn't nearly as hip as signaling support for less stringent penalties for some kinds of drug use. But it's necessary both because intellectual honesty requirks it and also because liberty without virtue quickly devolves into licentiousness -- and carries the risk of justifying creation of a bigger-than-ever-before government to pick up the pieces.