Why Fullmetal Alchemist 2003's Villains Don't Work

Fullmetal Alchemist 2003, for all of its strengths, I feel has one GLARING weakness that holds it back just enough to keep it from being one of my all time favorites. Fullmetal Alchemist 2003 consistently showcases trouble with writing antagonists, from the Homunculi Squad & their leader, Dante, to 2003's take on Kimblee and 2003 Original Frank Archer. Each antagonist has varying degrees of issue that all showcase the different approaches to antagonist writing, and how a writer can fall short in trying to write all of them. I had a whole month to come up with a better Thumbnail and I literally couldn't come up with anything (Edit from two months later: Alright I finally came up with something)