I agree with most of X's points. I don't like that they took a character that was iconic in pop culture, and decided to make him into something else. Why bother using Dracula as your villain then, if he just ends up being some guy named Mathias?
Also, I'm not concerned about what was written in instruction manuals of 8-bit games, whether Japanese manuals or English. Back in the 8-bit days, the games told their stories by showing, rather than telling, and your imagination filled in the blanks. If the original story intent was to invoke Satan, then why did you also clearly have Frankenstein and Mummies featured as bosses, if they weren't going for traditional pop culture Dracula as the big bad guy?