This year's primaries had 90 candidates for the 6 positions that had primaries, which is a lot of mess for voters to look at on a ballot. Also with candidates being able to put anything down for party it opens the doors for ratf***ing. Not that it makes it an always bad idea, but I want details.

My own personal bias towards open primaries is basically because the partisan primaries will often be biased candidates that appeal to partisans more than candidates that'll appeal to a broader base of voters. Also, only having a party's voters vote in the primary is easier to "fix."