Why does Nintendo still need Charles Martinet?

[Kenryoku_Maxis]

Using that logic, why do games need voice actors at all. Why don't they just keep using the same looped 'ARG' and 'AHHHH!' noises from Skywalker Sound for every game?

Its because people actually notice repetitive sounds and if you keep using the same ones, it gets annoying. That's why Rockstar has new voice actors for each GTA game and Konami records new dialogue for each new MGS game.

Short answer: New recordings for voices shows increased production values and increases sales. Using pre-recorded sounds shows lower production vales and can lead to low hype and low sales.