As someone who sees at least 1 movie a week, every week, I love the previews. One, just enjoy them, two, good time to get snacks (the food at AMC is shockingly good for theater food, and cheap compared to popcorn), three, running late is never an issue.
Love assigned seats. Have sat in M17 in the IMAX theater at least 60 times in the last 3 years. And have a screenshot for each of 18 theaters with best seats noted. Life is to short to sit in D4 in any theater.