John, I think your points are good. There is no question that the laptop is superior to the pen and paper for notetaking. I type much faster than I write and would rather take notes on a laptop.
But, with regard to the question of whether students are getting the full learning experience because of digital distractions, I'm not so sure I can satisfy myself by thinking it is the students' problem. As Robert Stacy McCain points out in a comment to the original post, I have the ability (and the responsibility) to set the policy. I may well go laptopless in my classes.
Mr. Chips isn't always a popular guy!