Sorry, I have more time to respond now -
just to provide background, my entire voting history is in a state that was only very recently dragged kicking and screaming into having an open primary. A closed primary is so far out of my experience, that I might be overlooking the good parts. And I admit, it might just be a purely emotional reaction.
I don’t think it’s any of the state’s business which party I vote for.
From what I’ve seen, (and please correct me if I’m wrong) when you have to register by party, it becomes part of the public record, and anyone can find out - I don’t think it’s anyone else’s business which party I vote for.
In primary “elections” where there is only one candidate, in a closed primary, the state (and anyone else) knows who I did vote for. That feels like it throws away the entire idea of a secret ballot. To me, that’s not in the spirit of a free or fair election.
I think having to request one particular ballot or another might surpress voters who live in an area where they aren’t in the majority.
I really don’t like the idea of paying for a private club’s elections - it bothers me that the parties are trying to have it both ways “we’re too private to let anyone participate, but too public to pay for it.” If you’re private, be private. If you’re public, be public.
Since a sizeable percentage of people are moderate and/or independent, I think that closing a primary eliminates their voice in elections. Especially at levels of voting where the election really is decided at the primary level.
I think that closing primaries give the two major parties way too much power in shaping the final outcomes in elections. And I have no idea how responsive or representative or accountable “the party” may or may not be to its members, much less the entirety of the electorate. I don’t trust them.
Even though it isn’t an election, the non-presidential primaries are often are mixed in with significant non-partisan primaries, ballot measures, other real honest-to-goodness elections, which makes them look like real elections and gives them the feel and gravity of an actual election. I find it disingenuous to hear “no, no, this part - just a nominating process. It’s different than everything else you’re voting for at the same time, using the same means.”
And finally, closed primaries make me shudder.