Bethesda wants to give gamers an enjoyable - and customizable experience - while playing Fallout 4, and won't rely on just pre-determined frameworks to get the job done.
If you remember purchasing a house in Skyrim, there was a minimum amount of customization available to gamers. That apparently won't be the case in Fallout 4:
"It's not just, 'Hey, here's Breezehome [one of the houses in Skyrim],' where we just picked a house, and you can buy it, and you can go to somebody and say, 'Here's this much gold, and put this thing into my house.'" said Pete Hines, VP of Marketing at Bethesda, in a statement to GameSpot. "[In Fallout 4] it's, 'Now I'm building it, I'm actually building the house, I'm building the wall, I'm placing the door, I made the table, I made the mattress.' It's that sense of making your own way in the world and defining, 'Who am I and where do I live and what's my story in this world?"