Many people who smoke weed want people to do it with, it helps justify their actions...this is not true for ALL but it seems to be true most of the time, especially in HS.
I don't think justifying their actions is the motivation behind a pot smokers will to smoke with other people, most pot smokers genuinely believe they are doing no wrong. I'd say it has more to do with sharing the experience with another person. It can make for quite a bonding experience.
I never have smoked it but my husband does. I was always taught how "bad" it is, but I never understood everything it did to a person. My teachers always told us that it makes you see things that aren't there, but people I know who smoke it tell me they never hallucinate when they are high. I read an article about a girl who smoked pot and then ended up smoking it along with crack or something like that and almost died, and the article was called "But It's Only Pot." That title misleads the reader; it wasn't "only pot" that almost killed her, it was mixing drugs. Anyway, the real reason I never smoked it was mostly just that I don't want to be laughed at for inhaling it wrong or holding it wrong or acting stupid or whatever. I'm very self-conscious and hate to get attention unless I ask for it. Plus I don't know what the consequences would be if I ever got caught, especially since I have three kids. I wouldn't smoke it around them because they are so young and innocent and don't need to be around something like that at their ages (2, 1, and 2 months), but I worry what would happen to them if my husband and/or I got caught with marijuana and got sent to prison, where would they go? I would be totally against them going to their grandmother's (my mother-in-law) because she's an abusive alcoholic sociopath.