Probably because both are true.
Resources being 'means and opportunity'. You need to understand that the vast majority of the Imperium never leaves their home planet. They don't have permission to do so. They are literally not allowed to leave their factory-slave job, and even if they could, what else would they be able to do on their two-Thrones-a-day job? Maybe if they were working for 50 years (hah! People in the Imperium don't live that long), and they get thrown out of the factory, they might be able to afford a trip to Terra. Maybe.
Which brings us to the next point; How do people even get there? How do you even get off your planet? Who is going to take you to Terra? Nobody 'just goes' to Terra. It's kind of a huge deal and is going to cost you a lot of money. Going to Terra involves cutting through huge swathes of red tape and TSA-checks turned up to 11, and no random passer-by starship is going to be up for that, and, if they are, it's highly unlikely that they've got time to pick up strangers.
Yes, and yes. Warp Storms will significantly increase travel time. A reckless Navigator can significantly decrease travel time.