I don't particularly hate smokers in general. I have way too many relatives who smoke to hate smokers in general. It's the people who inflict their habit on me that really piss me off. Like at college, every single door on campus smells like cigarette smoke easily 12 hours a day. The smoke is not just horrible for everyone on campus who has to enter that building, but what about the kids, like me, who have asthma, or maybe chronic bronchitis. I have to hold my breath when I approach a building because if I inhale any smoke, or much of the smell, it sends me into a coughing fit to match any chain-smokers, and my asthma is so mild it might as well not exist. Worse, people who smoke right next to the door are violating state law.
I also think that hating smokers is not so unjustified as you think. It is a choice, not a disease, yes it's addictive, but thousands quit every day. If you choose to smoke, I think you may deserve a little disrespect, maybe even hatred, because you choice negatively impacts the lives of all around you. Did you know, that even the left over smoke on your clothing, even if you smoked hours ago, can cause an asthma attack in someone with moderate to severe asthma? And for the rest of us, it's a very unpleasant smell. I for one, would rather have to sit next to someone with severe body oder, than someone who is a smoker.
Admittedly, many smokers didn't know the dangers of smoking when they started, and now they have trouble quitting, so they deserve a little slack. However, Smokers under 30 really have no excuse. They knew the habit was dangerous and disgusting when they started, and maybe some disrespect and hostility will push them towards making the healthy decision and quitting.
Also, a note on cigarettes "not being cool." This is true, but it isn't what's true that matters, it's the perception. And no matter how much our teachers say that smoking isn't cool, it's still a sign of maturity and coolness for kids in school. You can deny that all you want, but I have 2 sisters, a brother, and 7 cousins; out of 2 sisters, a brother, and 9 cousins; who started smoking because of peer pressure to fit-in and be cool. Of them, only my brother quit, the rest aren't motivated enough to move past their addiction.
tl;dr I don't hate smokers, cuz my whole family smokes or did smoke. I still think it might be appropriate to be disrespectful to smokers, and to hate those smokers who force me to hold my breath just to get to class, especially considering the fact that at it's a college campus, several people with asthma probably have to walk through that cloud each day for the same reason.