It is not only that. Smoking cuts across cultural lines - you can smoke with someone who have great difficulty to speak English (which would otherwise be a stupid situation). You can also have a conversation with very poor (manual labourers) without it being akward.

What is also nice is that you can meet people - by just asking for a light. Most smokers are extremely friendly to other smokers and if two people stands outside a building smoking, it is natural for them to talk. It is the new Freemasons.

I've sometimes wonder why tobacco companies doesn't embrace this with a slogan such as: "Smoking turns strangers into friends".