It doesn't fit the name of Pac-Man.
If he was Pac-Man Junior, I'd be fine with it. But he isn't Junior, he's the actual Pac-Man. It just doesn't fit the character in my opinion. I'd prefer some sound effects from the Arcade have that be it for the character's voice.
Bomberman, Rayman and Mega Man... all of them have "man" in their names, but they aren't real men.. and their voices (through the years, between a lot of voice actors/actress) aren't reflecting adults as well.. but yes teenagers, kids and even *ahem* girly in some way... there's no real problem with that, since they're all mascots.. they don't need to sound like a 40 years old man.
--and btw, the worst voice acting of Pac-Man, imo, was the one that he sounded like an adult man, in Pac-Man World 3.. geez... (the funny thing is that, when he gets hit, an "aw!" in, more or less, the same tone of his Pac-Man Party voice is heard,.. lol).
and another thing is.. (thanks to a reconsideration on the subject), NAMCO already has done a childish voice for him, even before his reboot;
Actually, he IS Junior, at least according to the lore. Pac-Man in the show is the implied son of the original Pac-Man and Ms. Pac-Man. That's why in the show they often refer to him as Pacster or just Pac. They rarely refer to him as Pac-Man.
ahm.. Bauske, this was really confirmed?.. 'cause, I never saw anything really consistent about that (actually, I ask gently, a source of this)... The only one, in fact, I saw saying something was Mike Chang (the NAMCO Bandai's marketing manager).. and he kinda talked with very little property, and not went too deep... and in any case, he was doing the marketing for the G.A. game, and nothing like that was cited in the show (or in the pre-marketing for the show). ... I actually don't consider this as a thing; since Zac and Sunny don't have any resemblence with the original Pac-Man and Ms. Pac-Man.. and both seems to be done for not having the relation with them, as well.
-- A reboot, after all, is for change things... and, Pac had his role and age modified in favor of a new public, the kids.. people who got used to have Pac as a family man, are already growed.. and don't need too much effort from NAMCO's part to make them love Pac. =)