I usually use it either for genuine helpfulness or for giving me a smile; either is a worthy achievement. I have probably thanked TAKTAK in the past, for amusement value.
I wonder if, this whole politeness thing is a perception issue though. I tend to find people are polite to me, and I tend to be polite to them. I thought that this was because I was lucky enough to live in foreign, polite, societies because I don't live in Britain, until I visited that benighted land last Christmas, then I found the brits to be much more friendly and polite than I had sort of imagined from just watching British TV and reading British papers.
I left Britain back in the 80's and seldom bother to return, and I had sort of accepted what seemed to be common wisdom, that society had degraded dreadfully, but I didn't see any of that when I was there. I just met nice people, like the one's I knew back in the 80s. I visited London, Croydon, Plymouth and Newark and it was the same story everywhere.
I think that a single rude act has a much greater impact than a normal, polite one, and that's why a lot of people perceive rudeness as common; we remember the silly cow acting snotty when we hold the door open or the bunch of dicks who stand chatting on a zebra crossing while you wait to get past, but we don't remember the vast majority of our human interactions where people are just nice.
There will always be those prats, but it still seems to me that most normal people are OK. Not as polite as the French, but easier to talk to.