While it's probably good not to have a crippling fear of talking to strangers, it's not something I really do unless I have a specific reason to. Like, a week ago I met a girl on a bus with a t-shirt that said something about tuk-tuks, which told me she'd probably been to southeast Asia and therefore probably interesting to talk to, so I commented on the shirt and that got the conversation rolling. Or if I'm at a meetup for people with shared interests, that fact is enough for me to want to talk to them and assume they want to talk to me.