I'm assuming we'll be able to punch with both hands though :huh:
I would consider that "dual-wielding," just like having a sword in each hand.
Swinging a dagger is more closely related to swinging a mace and a longsword. In all of those, your swinging an object thats in your hand. With H2H, your just swinging your fists/kicking if they would have added it and if they would have put more effort into H2H, it would be a lot different. Its already different enough. Swinging nothing in your hands and swinging a possibly 20 lb. mace are much different.
A mace (and all blunt weapons) are about generating as much speed as possible to do crushing damage. Daggers and short swords are much more stabbing weapons, with smoe slashing. Speed doesn't matter as much for damage, location is important, and it is designed to be drawn across the skill to slice. If you are using a dagger like you use a mace, you are not going to be very effective.
Maces/Swords/Axes are all going to have about 3-5 perks in the 1-handed skill tree. It makes more sense that H2H would have a couple there as well than having 10 or so in a completely seperate skill.