LOS ANGELES, Dec. 3 — The Walt Disney Company announced several changes today to its board, including one that could reduce the influence of a chief critic of Michael D. Eisner, the chief executive. Disney also said it was lowering its 2002 earnings estimate because of the disastrous performance of the animated "Treasure Planet," which cost $140 million to make but took in only $17 million at domestic theaters over the holiday weekend. As part of the boardroom changes, Disney will add a new independent director, Robert Matschullat, a former Wall Street banker and top media company executive. It will...