Emil Pagliarulo has answered questions for 1Up in a new Fallout 3interview. Let's take a grab on VATS:
1UP: The "Vault-Tec Assisted Targeting System" allows for very methodical combat. But you've mentioned that you don't need to use VATS at all. How viable an option is run-n-gun?
EP: You can play the entire game in first- or third-person without ever going into VATS. We never actually force you into VATS for combat. So if you just want to point your weapon and pull the trigger, go for it.
That said, the game is very much an RPG and not a straight FPS, so your effectiveness with any weapon is dictated by your skills, as well as the condition of the weapon. If you find a crappy laser pistol and you've completely ignored the Energy Weapons skill, don't expect to pull a Han Solo anytime soon, in or out of VATS.
Personally, I use the run-n-gun method to take care of the weaker opponents, like Radroaches, and VATS for just about everything else; mostly because I've become addicted to the gory cinematic playback stuff.
Sounds like he had a hard time trying to stay politically correct about how amazing Fallout was while hinting there's something so yesterday about liking it :
In my experience, a lot of these ardent fans are old-school PC gamers who don't like many — or any — console games. So an amazing game like Fallout will sit on a hard drive for a long, long time. A fan will play it, then play it again, and then keep on playing it until their PC dies…
I guess if you play consoles, you are just naturally more exposed to all the cutting edge games out there, and you can appreciate better what Beth is doing, bringing the franchise into the 21st century for the good of mankind and all.