I am a Sam fan, yes. Sam did indeed get back into hunting full time because of Jessica' death, not because of Dean, but Dean is definitely putting pressure. Note in the pilot he conveniently "forgets" that Sam said he had to be home in time for the law school interview. Putting "forgets" in quotes because I'm not 100% if he actually forgets or just decides to act like he did.

I can definitely understand not liking John as a father. He was neglectful.

My issue with Bobby is that I don't really think he was Sam and Dean's father. It isn't until season three that the comparison is ever made. In the early seasons Dean more than once said John and Sam were the most important people in his life - no mention of Bobby. I don't think he was around that much.