That's difference is due to accent. No matter how hard the voice actors try, they are not going to sound 100% authentic japanese, because they are American. I don't understand what you want them to do. If they put on a japanese accent, it would fucking ruin the dub and you know it. Imagine the English Iruka with a japanese accent. THAT would suck.

No no, my point is that countless people have thought that Naruto was pronounced Na-roo-dough. Which is completely wrong. At least their stressing the right part of the name.