Why would anybody? Whitening has no health benefits, it's just an appearance thing.
I can imagine it might even have negative effects in the long term..
No objection to people actually getting treatment for actual PROBLEMS with their teeth, of course. But whitening just makes you look a bit self obsessed. And like a robot.. some people do it to the extent they look like they have plastic ones
Might be differing values since I'm British. (incidentely this is the reason we have a 'bad teeth' stereotype, and not cos of poor dental HEALTH, as our record is very good thanks to the national health service. So this is a beserk button for me)