So basically what we're getting is that it's simply harder to dub than it looks. That's interesting. I thought you just roughly translate the language and simply dub it out on the mic. I honestly believed anyone with a right voice could do it. Ignorance on my part I guess?
Still, despite the "disconnection" and other difficulties, can't the actors just speak like how they do in their daily lives? With the exceptions like Cowboy Bebop (pretty much only dub I enjoyed) I feel that American actors are taught with certain standards which literally tells them not to speak naturally for the sake of viewers. I can't really explain it, but like the above poster said, everything just comes off as goofy to me.
It's not quite so easy as to just speak like you do everyday...otherwise everyone would be a great actor, let alone dub talent. 
And yes, as a generalization, there's a certain "bad school" of acting that tends to emphasize a melodramatic or overly emotive style. My instructor from college would call it "cranking". It's basically when someone just acts with their head and face without any support, emotionally or physically. What you get is sometimes someone who emphasizes things with their head, or someone who just is a little over-amped and comes across as...well...acting. Sometimes, boiling things down to their simplest level is the most effective way to communicate, and too often actors choose to over compensate rather than be truthful. One example may be if someone simply asked you, "You believe me, right?" as opposed to "You BELIEVE me, RIGHT?!?" Unless the person is overwrought because they're being attacked by aliens, I'd be more prone to someone who delivered the line simply and honestly.
Also, I think the good actors on stage or screen are the ones that really make you believe that they are somehow connected to what is happening and what they are saying, and doing the voice over work in a studio, I would think, removes the actor even more from what one would consider natural and easy. It makes the actor have to compensate in other ways...either by working at understanding the specifics of the situation at hand and suspending their own disbelief, having a very clear and honest motivation, or some other method.
Personally, I also think that there's a disconnect in Western thought when people think about mind versus body. To me, they inform each other and can't really be disconnected, but so much of our theater teachings make a big thing about working from the outside in, or the inside out, or from the mind and thinking.
Sorry...probably more than anyone really needs to think about, but I've had a lot of training in the theater so I've often thought about things like this.
