Honestly, I like how every game seems to have their own set of graphics. It identifies them as their own game and more so what the feeling of the game is.
It's like in Wind Waker, they chose to go with cell shading. Why? It was not only made for a younger audience, but it gave you an idea, or a feeling, on what kind of game it is. Now, I love Wind Waker, I love the cell shading graphics and I love the game. It's my second favorite, OoT being the first. I think that the Wind Waker graphics not only are kid-froendly, but they kinda make you look at the Zelda games from a different angle. Up until that point, all the graphics were more serious and realistic. Wind Waker turned that around, and that's why it was a huge sucess, I believe.
Twilight Princess was revolunitary because they are the most realistic graphics to date in the Zelda history. It identifies it as a game to be taken more seriously than Wind Waker.
I don't know how much of that made sense.....I'm not good at explaining things. XD But basically I'm saying that each game's graphics gives each Link their own identity, so I don't think taht graphics should be mixed because of this reason.