I have no problem with them selling burgers like this, and I'm completely against the notion of being forced to add a salad to it. I think the grey area though is in advertisement. If the burger is being marketed to the public as the next gotta have meal and you'd be foolish not to try it, how is that different than what cigarette companies been sued over in the past? And if the ads are in any away appealing to children, thats a whole other issue.
Not saying I'm for or against their right to advertise however they want, just think the issue is more than just letting people eat whatever the hell they want to eat.