I manage quite well with just the 18mm and 35mm Fujinons as a walk-around kit; the 35mm on a 16MP DX body gives you about the same cropping ability as a 28mm on a 35MP FX body.
The combination of X-Pro 1, 35mm and 18mm weighs only 820g against 1200-1330g for the D800e and a 28mm (depending which lens you have), and the Fuji kit takes up quite a bit less space in a bag.
You'll only get a D800e image down to a 5-7MB JPEG by reducing the size and/or increasing compression - thereby reducing quality and negating many of the benefits of the 36MP sensor. A Large Fine JPEG from the D800e is around 16MP.
That's not to say that a D800e isn't a great camera, even for walkaround, but some people might make a different choice