Since creating a fully living and breathing world for the players to inhabit is a time-consuming process, I have been feeding them background info as often as possible as it is relevant to the story. Like, when we created characters, I told them all about the history of the towns they came from, their cultures and encouraged them to create family backstories. I gave them a general history of the planet, a specific history of the continent we started on, and specific history of the starting town and surrounding areas. And of course I always tell them that if there is anything they want to know, I'll think about the question and write up some info that addresses their concerns.
My question is: since 4e is so combat-focused, how do I encourage out-of-combat roleplay? I prompt them to describe their critical hits and misses, killing blows and other dramatically relevant die rolls, but between battles not much happens. They barely interact with NPCs that show up, they rarely speak in character, they don't even describe combat moves unless I tell them to. How do I get players to become more engaged in my game world? I feel like since it's a custom world without an adventure guide, my players aren't getting a well-rounded experience. (I know some players are more into roll playing, which is fine but a dash of character interaction has got to make it more enjoyable, right?)