The main problem I see with a lot of the amateur animated films?

Voice work.

Sadly most people aren't Jeff Bennett or Mark Hamill or Lisa Ann Beley or the Dobsons (father and the two sons).  Voice acting is as much of a skill as acting visually and most people don't have the range to convincingly pull off two or more characters.  Even most voice actors don't (Gary Chalk, who's main role recently  was playing Optimus Prime/Primal almost always sounds like like himself) while those who do, like Hamill and Bennett, get lots of work.