The problem is resolution.
If you think about it, even with the greatly improved version of the dev kit, you are still only dealing with 960 x 1080. I imagine this would make it terrible for reading text or fine information spread out over a large visual area. You'd end up having to move your head just while reading one screen, let alone be able to see multiple screens effectively at the same time. At that point, you may as well just use virtual desktops and switch between them.
In real life, this problem happened to me with 6 actual monitors. Yes I could add more, but then it becomes more effort to move my head to see the additional monitors than it would be to just flip to another virtual desktop.
And yes, monitor space is one of those things that you never have enough of. Most of the time I actively use 3, but once in awhile I get into something where I'm comparing stuff together or monitoring something in real time, and I find myself running out of space.