Foolishness.
Dual-Wielding is a convention of cinema and video games that has led to a degredation of the art of combat. There is no "dual-wielding longswords" in real life. It's cumbersome, and has only ever been seen in history by fools who are quickly murdered on the battle-field because they decided to go out with two swords! The idea of "dual-wielding" blades (like guns akimbo) originally comes from early Hong Kong Cinema, as a stylization of fighting for action movies.
The idea of dual-wielding arises from Main Gauche Fencing, in which the "main gauche," a parrying dagger, is used in the off-hand. The Parrying dagger is usually a Poignard (but can also be a sword-breaker, or a trident-dagger), and the standard length is 22 inches en totale, with a 14 inch blade. Many parrying daggers can double as bucklers, depending on the size of the hand guard. Hand guards on parrying daggers are often very large, as the dagger is used to catch and deflect an opponents blade. Main Gauche Fencing became popular in the late middle ages and the early renaissance amongst the nobility, and was considered an art form, often depicted in illustrations of the time. However, this has led to uninformed appreciators of medieval times to think that it is useful to use two long blades at once. It's not. It's suicidal.
The samurai had a similar form of combat to the Main Gauche in which they wielded a katana in the main hand and a wakizashi in the off-hand, but it is still dagger and sword combat, with the dagger used for parrying and surprise attacks.
I have loved the Elder Scrolls games not simply for the story or the cultures, but because they don't rely on the trite fantasy conventions that so many video games like Dragon Age and WoW fall prey to. There is sword and shield combat, there is single weapon combat, and their is zweihander combat. There is none of this fantastical, unrealistic bull-[censored]e that is Dual-Wielding. The Elder Scrolls is above such things. And in this sense, I respect TES for following realism, and not popular opinion.
(I would approve of dual-wielding a dagger and a main-hand weapon, however)
Please keep your realism out of my fantasy game play, and your comment is actually contradicts itself a bit. You like good ol' sword and shield combat cause it's realistic, but don't mind the fact that you can hit an enemy with an enchanted sword and they turn into a fireball, but wait, lets take that down a notch. Is it realistic that a sword penetrates heavy armor at all? I've seen Katanas slice 2 pigs in half at the same time.....when that same sword tried to penetrate chain mail, it didn't leave a scratch. The realism argument really holds no water in this game. I am actually surprised that people are against dual wielding......how naive of me. looking back I shouldn't be surprised. I haven't seen one idea on these forums where someone says "NOOOOOO!". But every great idea is usually met with resistance.