I've done ribs with no rub at all and was surprised by how good they were. I had to trim some back loin ribs to fit my 18 WSM so I tried various rubs on the trimmings and left one plain as a control.
Try it! I doubt you will be disappointed.
I also highly recommend trying different smoking woods (without any rub) to see what flavors they contribute. It's very instructive to see what different things contribute to the flavor profile you are trying to achieve.