(To be fair, I do not see primaries themselves as a problem - just having to tell the government which primary you vote in, AND also considering this a "party affiliation".
Things might be different if lots of people strategically set the _other_ party as their "affiliation", only to then show up at their primary and vote for the candidate least likely to win the general election (or most palatable to them as a plan B).
If a significant amount of people did that, then the field in the voter registration would not be very useful for retaliation purposes.
But now we're deep in game theory...)
