This isn't judgment against smokers. This is a fact of life.
Physical (and mental) health is the root of your being. It's easy to not worry about health when you're healthy. There's simply too much science and too much observation of the follies of smoking as a habit to say, "sure, go for it!"
The beautiful thing about life is that we have the freedom to make these choices. But with that freedom comes the responsibility of the consequences of our choices. If you get it right, you enjoy the reward of harmony. If you get it wrong, you suffer. And with the body, much of the damage we do is not reversible.
Smoking as a habit is simply unintelligent.