I mean, it was probably more a conscience decision for MS than anything else. They wanted a quiet, nondescript design that fit in with set top boxes from cable and satellite companies. They could have made it smaller, but why bother, their target audience isn't going to be putting it in their dorms/bedrooms.
From the other views, it seems the PS4's length is more than its height, so the comparison image really puts the PS4 in the best light. But the PS4's planform area is still smaller than Xbone's, and it's not as wide.
As someone mentioned in another thread, it's a good idea to have it deeper than wide. On a shelf usually you have limited width space but extra deepness* space. The only thing you'd be competing with back there is cords or on a small skinny shelf it's probably best not to put a console on it, and you can just stand it up and turn it sideways probably (still wouldn't be as long as XB1). WiiU is deep too, maybe the Japan devs realize shorter but deep is just better for shelf space.
Even though the PS4 is longer, overall, it's far more aesthetically pleasing to eye for many here. It looks something out of the future (well it kind of is). And the Xbone in comparison looks as industrious as ever.
Had I never seen the PS4, the Xbone design would have grown on me.
The 360 skews the truth I think. Other than the Xbox 360 first model's failure rate, Microsoft has a pretty damn great track record on hardware, both design and function. Well not the first Xbox's design. Ugh. I never liked that. But the surface, arc mouse, natural keyboard, going back to old Sidewinder joypads and god tier Force Feedback Sidewinder Pro.. all awesome.
Alright, here's my attempt at a to-scale picture, based on the size of the HDMI ports. Xbone picture was perspective cropped from a shot someone took of the box, since I can't find an official high res picture of the back.
As long as it doesn't overheat and we run into another RROD issue, then it's just a beautifully designed box. Smaller, more powerful, and an internal power source. My only concerns besides heating would be how quiet it is.
Come on guys I thought everyone would've sussed it by now. The xbone is made purposely huge, it has vast amounts of empty space inside. It has a banana to check for the 1 year warranty, and so to prevent the smell getting out as it ripens and rots thy have a big ass fan.
In 18 months when the xbone slim comes out, MS can then make it much smaller by cutting down the empty space and then even smaller from making the parts smaller. Then they can say "GUYS LOOK THE NEW XBONE SLIM IS NOW 4X SMALLER" and people will buy it in droves.