Beyond this, characters are strong and capable straight from first level. In 3E D&D, a first level character stands a decent chance of being rendered unconscious by one successful attack. A first level wizard stands a decent chance of being rendered unconscious if someone sneezes on him. And that wizard can cast one, maybe two magic missiles per day before he needs to go rest. It's hard to start like this and feel like you're Indiana Jones, or a hardened war veteran. Especially when after you kill a few goblins, your hit points and BAB double. If that's all it took, why didn't your war experience get you to that point?
By comparison, 4E characters begin tougher and progress a little more slowly. By the time you're fifth level, you may have doubled your hit points as opposed to quintupling them. But at first level you can take a few hits, and as that wizard you can always throw a magic missile (even if you need to catch your breath for a few minutes between casting your really impressive spells). You've got more options and abilities... it's easier to imagine that you are Indiana Jones, or Daine, early on - as opposed to feeling like an apprentice waiting to kill a goblin or to to get that "Ding".