Superman and the Marlboro Man

It was during a re-showing of Superman II a few nights ago that it dawned on me how often Marlboro was used as a product placement during significant portions of the film.

This of course brings to mind how far the anti-tobacco movement has come since the days of Superman. Smoking is banned in restaurants and some bars. You rarely see a tobacco advertisement. While I am definitely not a fan of tobacco it raises an enigma in my own mind? Why is tobacco seen as a negative while marijuana is pushed heavily?