For one, life is an experiment, really. You do not go through life calculating every step of the way. What was that poem on the school notice board that told us many things that life was and what needed to be done with it? Knowing your calling and being able to execute it in a planned and rhythmic fashion is not just improbable, it is plain boring. People walk through life - sometimes things go right, sometimes they don't. That should not mean that it's a crime to make mistakes, screw up, feel the heat. Taking the wrong turn is also quite a big part of life.
When Mr. Jobs talked about the dots connecting backward, what we probably need to remember is that there need to be dots to connect. That brings me to fallacy number two - if I sat all day thinking about the philosophical question - "What should I be doing in life?" I'd remain where I was - I wouldn't change at all. Worse, I'm losing valuable time when I could have tried out things inspired by my tendencies. At least I would know if I sucked at something even though I had a fantasy for it.
Three, a man's got to be practical. Sometimes, doing what interests you is not what is in the best interest of the people surrounding you. That need not mean just one's family. Following a dream many times means taking a risk - it is defined by the thin line between a hobby and a career. I also believe this gets complicated by the fact that most people aren't interested in what they are good at and vice versa. While it's what you are good at that gets you two square meals a day.
That said, losing oneself in one's limited world of practicality is probably uncalled for. Dreams are to be pursued, passions are to be stoked. No question about that. Only you can't start pursuing your calling at the press of a button.
PS: I wrote this because I talked to a lot of people about what's important for them and why they aren't doing what they claim interests them most. Most people, including myself, gave answers that were attributable to one of the above. It sounded very confusing because when I was studying, I came across a number of people who criticized being very conventional, "taking pressure", not living life to the fullest, etc. But when it comes to the real game, apparently life takes a U-turn. Do let me know what you think.