It's worth noting that the caucus is supposed to be much more than just registering your presidential preference. The idea is that you have a regular gathering with your neighbors to discuss political concerns. That most people view it as an elaborate and slow version of a primary is an indictment of how sad the state of political participation in our country is.
That being said, it is an excellent way to exclude people who have other responsibilities or difficulty making it out for several hours on a week night.