Hardly that simple.
Just that those people who love the Fallout series want to see those traits they loved brought into the next incarnation of the game, however Fallout 3 was lacking in some of those aspects. I still very much liked Fallout 3, but it doesn't follow the theme of Fallout and Fallout 2 very well.
I feel they can keep a lot of what Fallout 3 is, but add some depth to the game. Something a bit more substantial to it.
Would you consider that "doable" as it probably wont be turn based? Isnt that where a lot of the charm came from wrt FO1 and FO2? I dunno, I havnt played any of them.