I say leave it there. It's innocuous enough, and it'll be valuable demographic data later on. If you stop asking for it now, and then need to start later then

I say leave it there. It's innocuous enough, and it'll be valuable demographic data later on. If you stop asking for it now, and then need to start later then people will be suspicious, and you'll have holes in the data from when you didn't ask. Of course, with all user submitted input, don't ever assume it to be right. ;-)