I did a test earlier today and found that my two-handed weapon swung faster than both of my one-handed weapons did when dual-wielding and using both at the same time.
Given that the damage between a two-handed weapon and two one-handed weapons is about equal, the two-handed weapon gives a higher dps. In addition it's possible to block using a two-handed weapon and not possible to move while swinging both one-handed weapons simultaneously. Is there any case to be made for using dual-wielding as opposed to two-handed? Am I missing something?

One of the talents in the 1-handed tree speeds up dual wield attacks. It has 2 ranks at 20% and 35% I believe. Did you take that into account? Combined with elemental fury you can attack so fast that most things die within a second or two. I found dual wield to be extremely powerful.

Dual wield for higher damage, 2-handed for less damage than dual but more than single 1-Hand + being able to block.

I tried both, didn't like two handed. It's too slow for my liking, and the damage is abysmal aswell.

I actually like two handed a lot. Running it on my Orc. Works great.

Good point.
The talent trees for one-handed and two-handed appear like mirror images... in both axes cause bleeding... in both a running power attack...
The major difference between the one-handed and two-handed perk trees is the dual wielding branch of the one-handed tree, enabling 40% speed increase at skill level 30 and 50% bonus damage to power attacks at level 70.
So, they could become better, I guess, given enough practice and time.

Also, if one plays on easy mode then it doesn't matter what weapon one chooses because all the enemies die anyways.