"I just don't think Lynch's Dune can be objectively defended as a good film."

I agree with you and accept that my love for it is entirely subjective. As a child, I was lucky enough to have two older brothers with whom I routinely hitched a ride to a lot of scifi. I saw 2001 when I was seven. Mindblowing and objectively good. So, I saw Dune well before I knew what a screenplay was or who Frank Herbert was. It clearly left some impression. I almost watch it like a music video now. I know all the words and sing along.