Hospitals should be as healthy an environment as possible, so it made sense to ban it there. Aeroplanes already have enough problems with air filtration, so it made sense to ban it there. In theatres and cinemas the fug tended to impair the view (the prime purpose of the experience), so it made sense to ban it there. But the total ban on trains and buses was already a step too far - apart from anything else, I would sometimes hit the smoking carriage just because it was easier to get a seat.
The ban in pubs is, like the (theoretically still law) ban on swearing in pubs, an unjust imposition for somewhere which is meant to be a place of relaxation. I've nothing against non-smoking pubs, maybe even giving them tax breaks - though it's noticeable that in all the time I was in Cambridge, nobody ever suggested going to the Free Press, and business in the smoke-free Wetherspoon's has been way under expectation.