I think the thing is, that when people pay like £15 to go to the Cinema, they're expecting value for money and stuff they wouldn't just see in a TV episode. They want to see things that are spectacular, they want plots with high stakes that affect the characters, they want characters that are well written they can empathise with, and they want to experience catharsis (an ancient Greek theatrical term for the release of strong emotions to cleansing effect) and to come out of the cinema like "...wow. THAT was a movie."
If I went to the cinema and it was just like... 90 minutes of inconsequential fluff like watching three episodes of a normal cartoon but maybe with better animation because the stakes are low and character development was kept pretty minimal, I'd probably be like "....why was this a movie?" If big things don't happen that create big stakes and big emotions, it's like... why is it a movie and not a short sitcom series on netflix?
And I think the people who fund movies, not just animated ones, but all movies, have the same mindset. If it's got the plot and stakes of a sitcom or a cartoon episode, and only leaves the same emotional impact as an average sitcom or cartoon episode it should be a TV show, not a movie with the kind of money a theatrical release involves or demanding £15 a ticket.