The word "mature" has been thrown around so much in the Wii vs HD debate, same as the word "hardcore", that it has lost any fixed meaning.
To me a "mature" Zelda means a more realistic (graphically) game. Voice acting is a way of making it more realistic. But it is a matter of cultural preference. TWW was more accepted in Japan than it was in the West. I've always a Zelda fan, but I remember when the N64 demo came out with a more realistic Link. I remember thinking how awesome it was. Then when the GC came out I was imagining an even more realistic Link, but instead we got an animated look. The game was great but the style was not expected.
With TP I was glad at the more "mature" look and I loved the game. But I can still see some of the "drawn" style in the chaacters. A bit "anime" or "manga". So I believe that is what the G4 people mean when they say a "mature" Zelda.
"¿Por qué justo a mí tenía que tocarme ser yo?"
