I always felt fallout was about no-compromise roleplaying.

GTA is my favorite foil to Fallout; In GTA you can beat a hooker to death with a baseball bat, kill as many cops as you want, but If you can run away fast enough, There are no consequences.

In Fallout 2, if you kill a kid, people remember you. You do enough bad stuff, People from other towns (who have never seen you in person) will run away, start throwing rocks and shooting at you. The karma meter in Fallout really enforced that role you choose to play. (on a similar note, I did wonder why you could not win over a town by giving food/money directly to townsfolk and/or children)

Although I'm sure Fallout is still an awesome play, I think by removing children from the game Fallout loses a little bit of what has made the franchise great.