cause some huge japanophiles obsess about having japanese voices even though they don't speak japanese because they feel it is acted better.
Maybe a lot of people simply prefer the original language? I know I do, whether it's Spanish, French, Japanese, German...whatever. The way some characters, including main character Naruto speak, also seems like it wouldn't translate the same way into another language other than Japanese.
...But I'm getting too deep into this. With this game, we know it's just JAPANOPHILES "JAPAN OMFG SPLOOGE."
I assume the real reason for the voices is for an eventual Japanese release. The game can come out and sit on the shelves with the hundred other Naruto games being released alongside it.