"open rates are arguably the most ridiculously stupid metric in the history of marketing"

Well, according to Ken Magill they are. While I agree with him on some points, notably the inflated value most marketers place on them and other industry metrics, they do serve some benefits.

These include providing a clue to whether your audience is even interested in your email. Sure, there are some issues with Open Rates (image suppression, preview pane) but I like using the stat the same way I like looking at my fantasy basketball team's rebounding totals. It tells a small part of the story and everyone loves stats anyway, especially in marketing and fantasy sports. But do you make a huge change or trade your best player because of this one isolated metric? Of course not.