I think, based on the very limited exposure to the voice Pratt is going with, that they've actually made a smart choice. Mario's voice in the games works in the games, but to utilize something that silly (and, let's be real, stereotyped) for an entire movie would probably be pretty grating.
Pratt appears to be going for "just a regular East Coast guy who happens to have Italian heritage," and I think that could work fine.