I agree, Jefe. I don't think a Thank You note is necessary, either, but I personally believe in sending them anyway. If an interviewer gives you negative reviews because they don't get a note from you, the interviewer is petty and the school certainly knows it. If it is a school with integrity, it will not put as much weight on the petty interviewer. If it is a school that is concerned only with outward appearances, then you don't want to go there anyway.
Still, I sent a Thank You note to everyone who interviewed me because I really did appreciate the time they took to talk with me. They aren't paid additionally to be on the AdComs--it is something they do because, for whatever reason, they want to. The suggested note that I offered previously was the general framework of what I wrote in each thank you note. I personalized each one--I said specifically what I liked about each school and told the interviewer that I particularly enjoyed discussing X, Y or Z. Of course, some of these were easier to write and were more heartfelt than others--if so, the note took a completely different tone. (These are the notes that write themselves!!! They are also usually slightly less formal...) Either way, it is a nice gesture to thank someone for taking time out of his or her life to talk to you to help decide whether you and the school make a good match.
So, while it is not necessary AT ALL to write a note, it is a nice thing to do--if you feel it, do it!
🙂
mma