I think they had to in order to make the movies the way they are now. I mean, if she was like she was in the first movie, she wouldn't have done anything such as look for chomper, go after the bullies, helped Littlefoot search for the night flower, cared if they got seperated in LBT 5, searched for the stone of cold fire, let MR. Thicknose come along in LBT 8, even been persuaded to help Mo get back to the big water, or even go after Littlefoot in LBT 10. Her personality changed a lot from just movies 1-2.