This is my *opinion* only:
The essay portion of the PCAT is rather new. Most schools are not really sure how to view the score, or use the essay for admissions. Schools can use it as a potential writing sample, but I dont think they will ask you any questions directly related to it, because you probably wont remember anything you wrote on it.
As far as I know, the PCAT scorers are looking more for having a fully fleshed out essay with limited grammatical errors. If your actual content is brilliant or horrible doesnt really have a bearing on your score.