By far the most common type of open primary is one where Pubs, Dems and Ind can vote in either the Dem or Pub. Which gives everyone the opportunity to vote in the primary of their choice. I took exception to your post because you made it sound like this type of primary was common when it fact it’s only being used in two states (three if you include the hybrid in Alaska). The movement does seem to have a bit of momentum but as I said the proposal was just defeated in Arizona and Nevada.
I wouldn’t mind seeing a tradition open primary like we see in most states. Not sure we’re ready for the type being proposed. Arizona and Nevada certainly weren’t. Should be put to a vote though