Didn't know John Carter was planned as an animated feature at one point. Who knows, maybe it could have been a blockbuster if they did the marketing right.
Also found this about the John Carter movie that never was:
https://www.mouseplanet.com/9831/The_Di ... Never_Were
In 1992, director McTiernan brought on another writer, Sam Resnick, who had just finished scripting a well-received made-for-television movie about Robin Hood starring actor Patrick Bergin that McTiernan had produced.
Actors Tom Cruise and Julia Roberts were offered the two leading roles. Cruise apparently did not care for the script that he was shown.
McTiernan became convinced that, in order for the film to be successful, instead of disguised elephants and camels, most of the effects needed to be done in CGI (computer generated imagery). However, in 1990, CGI was in its infancy and so was highly expensive and time consuming. In addition, CGI was not as advanced as it is today in terms of creating realistic, organic creatures.
Several sources have claimed that Disney determined that the final budget for the project with the salaries for McTiernan and the stars added to the amount necessary for all the special effects was estimated at nearly $120 million, making it one of the most expensive films ever made.
Which is probably the reason why they wanted to do it as a hand-drawn project instead.
A year later, Disney made one final attempt to take a different approach with two new screenwriters. They brought in novelist George R.R. Martin, perhaps best known today as the writer responsible for the series of novels that inspired HBO’s television series A Game of Thrones. The first volume in that series was published about three years after his work on this project. In addition, Disney also brought in science fiction novelist Melinda Snodgrass. At the time, she had recently finished writing several episodes of Star Trek: The Next Generation and served as story editor for that series during its second and third seasons.
(Martin and Snodgrass had also cooperated on the book Windhaven a few years earlier.)