I'm not sure how important "semi-realistic" art direction was to sales for Ocarina and Twilight Princess. It probably had a lot to do with the greatness of Ocarina, and several other reasons for Twilight Princess: launch title, novelty of motion controls, huge install base, etc.
On a personal note, I wouldn't mind if Nintendo EAD reused the art style of Wind Waker with a new Zelda game. In my opinion, Wind Waker has the best production design of any game in the series.
Edit: post #1,500!