Now, I am leaning on my memory of previous caucus vs. primary fights, but this is the crux of the debate. Primaries are fine (according to the parties) but, they should serve the parties, not the voters. In this case, its a matter of making the primaries closed to only partisans. Or, at least partisans that will declare themselves publicly.
In that case, the parties get nice updated lists of registered voters that will pick a side. And, those voters will get mailed to, hit up for donations and cajoled into supporting the parties and candidates.
And, unless those lists are strong (and with cross over voting allowed under the old system, they're not) its not worth it for the parties to go along (at least in large part). And, this is how we get the caucuses.
Because, if the parties can't get mailing lists, they should at least get volunteers.
This old presentation from the 2007/08 presidential season really spelled it out for me. While partisans will often talk about the grass-roots and participatory nature of the caucuses, what they're really about is foot soldier recruitment. If you find someone who is excited to attend a caucus, a good number of those folks will be good for other work.
From the presentation:
Every four years thousands of new Democrats attend the caucuses.Don't get me wrong. I'd rather have this political party than one that depends on mailings and over the air ads. It isn't bad to get people involved in politics and recruit foot soldiers. Some of my happiest and fulfilling public moments were at Democratic party meetings. Its good stuff.
Hundreds of them work on that year’s campaign for President, Governor, Congress, Legislature, and down the ticket.
After the election dozens of these new recruits come around to our monthly meetings.
By February or March or April a handful of new recruits are active in their local Democratic party.
But, don't also mistake that if the parties do commit to closed primaries here, that they're going to replace the excitement of the caucuses with some other sort of grass-roots event. It will not happen. They delegates will be chosen by a state-funded primary, all the energy from the caucuses will be lost.