I think the threat of unapproved candidates winning would lower a voter's approval threshold to include other candidates. Increasing the approval threshold happens when the voter likes all of the candidates, in which case there isn't too much of a problem.

I really want to believe that ordinary people can handle STAR voting. Not too far from product reviews: most will initially vote 5, 4, or 0. As long as the system encourages more honest voting (instead of lesser-evil voting), it can help fix our corrupt political system.

Full agreement with multi district/proportional, but I don't know how to sell it to normal people (they want THEIR representative).