Good golly do people get riled up by the idea of sending a thank you note after a job interview. "Why should I thank them, they didn't give me a gift!" is a common refrain in /r/jobs.  "They should be thanking me!"

I think the big problem is the name, "thank you note."  It makes us recall being forced to say nice things about the horrible sweater Aunt Margaret gave us for Christmas.

It's not a thank you note. It's a followup. It doesn't have to be any more than this:

Dear Mr. Manager,

Thank you for the opportunity to meet with you today. I enjoyed the interview and tour and discussing your database administration needs. Based on our discussions with Peter Programmer, I'm sure that my PostgreSQL database administration skills would be a valuable addition to the Yoyodyne team. I look forward to hearing from you.

Sincerely,
Susan Candidate.

There's nothing odious there. You're not fawning or begging. You're thanking the interviewer for his time, reminding him of key parts of the interview and your key skills, and reasserting that you are interested in the job. (And before you say "Of course I'm interested, I went to the interview!", know that perceived indifference and/or lack of enthusiasm is an interview killer.)

People ask "Do I really have to do that?" and I say "No, you don't HAVE to, you GET to." It's not a chore, it's an opportunity.