simple as that :
1 - Japaneese Voice Actor puts feelings into the role he/she plays.
2 - English Voice Actor puts effort into the work he/she is doing.
1 does not equal 2
even if you put the effort of a galaxy, you can't replace feelings with effort, no matter how good the VA is if there are no feelings the effort is wasted, that is why English dubs are so horrible, there is no feelings in them, only effort because they are paid, Japaneese on the otehr hand, love this kind of job, it allows them to experience different personalities, they can behave differently, it gives them another piece of their beloved freedom, take Saikano for instance, the lead female VA is timid and incredibly polite, but in the show she plays the role of a girl that is not herself, a quite different character to experience, this is what makes Japaneese original dubbing so unique and pleasant to listen, same goes for Higurashi, the VA of english dubs is not bad, but l always say ENG DUBS ARE HORRIBLE, because l don't feel anything from listening to them, in the most touching scenes in Chobits l didn't feel anything when l was listening to Eng dubbs, while l cried a bit when l listened and read the subs form jap dubb.
to me this matters the most, it doesn't matter if the voice is similar, and sounds good, if there are no feelings, the effort is wasted, and that is why it's a horrible english dubb.