Silk Spectre II Forced To Quit Smoking For Watchmen Movie

Looking at the different images and trailers, we can see that Zack Snyder went all out in creating even the smallest details to resemble the graphic novel adaption of Watchmen.  It turns out there is one detail that was left out.  Laurie Juspeczyk's character (Silk Spectre) smoked a lot in the book.  In the movie, she seems to have kicked the habit.  What was the reason for this?

It turns out that Alan Horn, the President of Warner Bros, hates smoking.  It was okay for the Comedian to smoke since he was sort of a 'bad guy.'  Zack Snyder even said, "I was sad, but it was either that or...the movie wouldn't have been made, literally."

Wow.  She did smoke some weird looking cigarettes.  At least her cigarette pipe thing was weird.  I'm no expert on smoking so I'm not sure of the point. 

Is this a big deal?  Should she have been allowed to smoke in order to stay fully true to the book?