I watch SF Nextdoor (because my Supe told me it's important to him), and damn Nextdoor users hate the Great Highway Park proposal.
My take is that many folks hate it because they can't visualize it. I think we need more concept designs than are on https://www.greathighwaypark.com/, allowing people to see what beauty they'd gain from having it. They have a sense of loss, but not gain.