Nearly every one takes notes on laptops during class. You witnessed a torts class (not mine, obviously), which apparently has been the outlier 1L class this semester in every section. They've been run/taught differently, with the newest professors, with a heavy policy-spin, rather than tailored toward the black letter law. My guess is that the class you witnessed already made up their minds that computer notes were probably not necessary.
In most classes, however, computers are nearly common place. There are still some students who insist on taking notes by hand - and it can be done. To the best of my knowledge, Penn does not require a laptop (though I can't imagine handwriting exams, some people do). If you do want to do without one, I'd say go for it. Some of my best friends take hand notes
P.S. Computers do prove very, very tempting.