I'm just watching Washington Journal on C-Span, as you do. They featured an article (titled as above) in the Washington Post which chronicles the history of the primaries and caucases in the States. The commentary, by Sean Wilentz and Julian E. Zelizer, notes the weaknesses of the current system:
The old ways were unfair and autocratic, of course. But the new ones have grave problems, too.
For one thing, caucuses can be highly undemocratic. They eliminate the secret ballot, forcing voters to declare their loyalties publicly, and are thus vulnerable to intimidation and manipulation. They also shut out many citizens who have to work during caucus times. If you can't show up at a specific hour, you can't vote -- a particular problem for people with fixed shifts, including many of the working poor. (The supposedly democratic caucuses can also discriminate, as happened to Sabbath-observant Jews who couldn't get to Nevada's Saturday caucuses.) And there are usually no absentee ballots, of course.
..."Open" primaries and caucuses (in which anyone can vote, not just registered party members) let voters from the other party cause all sorts of mischief. A Republican convinced that Sen. Hillary Rodham Clinton is too divisive to win in the fall could vote for her in some Democratic contests in the spring, hoping to saddle the Democrats with a losing nominee. Or, as Sen. Barack Obama's campaign did in Nevada, a candidate can openly appeal for votes from people outside his or her party in order to stop a rival. The winners are outsiders hoping to game the system; the losers are rank-and-file party members whose choices count less.
The article concludes:
The unintended consequences of the well-intended reforms of the 1970s are now glaringly clear. Perhaps now, both parties will agree to reform the nominating system once again: abolishing caucuses, regularizing a rigorous system of national debates, closing open primaries, grabbing power back from the media and so on. We could still get it right in 2012.