I have to disagree on this one! I tend to drive around with my fogs on a lot for a few reasons.
They slightly improve my visibility - I drive mostly on unlit country roads, it helps to be able to see the edge of the road, and the fogs cast a much wider light than the dims. The 406's dims aren't great and I'm thinking of adjusting them - heads are amazing though. They're so bright that the glare from road signs with the heads on is almost unbearable sometimes.
They improve my chances of being seen by other road users, especially around twilight when the sidelights aren't much help, again I think they're just a bit too dim to be spotted by some people - I drive by the rule that everyone else on the road has an IQ of 40
I don't find them at all bright enough to dazzle, even in pitch black conditions and up very close.
Fog can roll in in a matter of seconds here as I live on the coast. Additionally I tend to drive a bit faster at night as I can see others coming a mile off so it's handy to have them on already if I go flying into thick fog. I just have to turn the heads off and don't have to worry about fiddling around and looking down for the button for the fogs instead of watching the road.
I do get it with people driving around with rear fogs because like others have said, on some cars you don't know they're braking or not. But I don't understand all this fuss about front fogs! They're not even that bright!