it'd be kinda hard to do much backstory on a character unless it's an episode about them. They only did flashbacks to the day of the flight, and it'd feel too tacked on for them to talk about why this or why that when they're trying to blow open a hatch or run from The Others or whatever.
I think they showed enough of what's in the hatch. If they'd shown much more, it wouldn't be much of a cliffhanger