My mom and dad made me write handwritten thank you notes for all of my Bar-Mitzvah gifts. Tamar and I did it for our wedding as well.
We still try to, but admittedly there are times when we default to a quick email note.
Today, however, I was on the receiving end of what was obviously a mass distribution acknowledgement note (the person's parent had passed away).
That's crossing the line, IMHO. (in my humble opinion)