sheesh. ok time to get schooled spuds.
the legend of zelda has been based on the same characters and almost identical events since it's inception. this has been done on purpose...link is, if you will, a hero who has to keep completing his same quest repeatedly. think of hades a little bit (each person relives their own personal hell over and over).
now, the reason for this ties in and is even more or less explained at the beginning of wind waker. this story has become legend...it is a timeless tale. think of each game as being a different "telling" of it, as we all know how legends can become so many different things when they are told across the ages.
no, this is not an absolute truth, but this is what goes into a lot of what LoZ is about. to utilize the different graphical approach was two main things.
A. they were going to be using huge, wide-open spaces (all that water, and no load times). they needed to be able to render that quickly and effectively without using fog or the like.
B. it also served as a means for showing a different narrator telling the story. If they had just overhauled the majora's mask engine and tried to make things look realistic, it would have been boring. I for one enjoyed the cartoonish animation, from the smoke effects, to the stylized almost nordic appearance that many of the things in the game looked.
link is a time traveler...but also travels in the 5th dimension by being timeless. this is what enables him to basically do the same stuff every game and not get boring. the cel shading kept things looking fresh.