Last year I went to a meeting on the east coast of USA. I applied for an ESTA, and when the application form asked for a "U.S. point of contact" I put down the work address and phone number I had for the meeting organizer.
Now I'm going to the west coast for a different meeting. My ESTA is still valid, but there's no way to update the point-of-contact information.
It is quite well known that I don't need to update this information. I don't doubt this. (At least I very much hope they're not going to call the guy who organized a meeting in Boston last year if there's a problem with my entry at San Fransisco next month ...)
But I'm curious: Why do they ask for this information in the first place, when it will predictably be out of date for many arriving travelers? Is there any official word on what this is for?
[Note that this is a different field in the application than "address while in the U.S." which I can change for a subsequent trip].