Because civil liberties and cultral customs should not be attacked by government.
OK, smoking is bad for you, so is driving a car you can die in an accident, so is crossing the road you can get hit by a bus. So is alcohol, so is fatty food. Many things are bad but in moderation people enjoy them. If you enjoy something ,even something statistically bad for you, it might not actually be so bad after all. If someone is going to abuse something no law will change their mind. Banning smoking across the bars, restaurants, offices ok, its not pleasant and smokers are diminishing in percentage, ok its understandable, but making the ban an absolute blanket ban with no exceptions (apart from the parliment building which is too cynical to even think about, one rule for them and one rule for us.) was over done.
There used to be around the country especially in Marble Arch, London, tea shops that sold hookahs to smoke, a totally different kind of tobacco use to chuffing 40 Malboro a day. They were open 24 hours and most being run by muslims didn't serve alcohol.
They are a middle eastern cultural highlight of London, they are open late and make a perfect place to end the evening at 2-3am, rather than in some sterile night club buying over priced cocktails and ending up plastered for no real reason.
Some still manage to eeck out a living with people outside in the rain on the pavement, trying to enjoy their water pipe that can take an hour or more to smoke, but the fact is that people visited those places for the sole reason of enjoying a water pipe, its not something you are going to load up at home or even do on a daily basis. Its not that terrible or addictive, and why would you want to go and infringe on peoples civil liberties to enjoy a cultural pastime.
Polo playing or motor racing is probably more likely to get you killed than smoking the odd Hookah is that banned ?
If people gather in a place for a specific reason of their own free will, and all are there for the purposes of enjoying a water pipe, or I suppose in other cases a cigar, or even smokers want to gather and have a beer together, why should that be banned ? If everyone in the room consents to smoking taking place, what right does the government have to march onto private property and declare its banned ?
Couldn't a tea shop that offers hookas, or a cigar bar, or even a popular watering hole that is mainly frequented by smokers be able to apply for a permit to have smoking. ? There is no reason why this shouldn't be allowed.