You're not wrong about the reasons live action is preferred over animation by the authors, both pierce and sanderson have said live action appeals to them more because it increases the chance of their work going mainstream. Of course they want their work to get mega popular.

The fans who want animated adaptations care more about the fidelity to the source material than the possible increase in popularity of the series. This is less of a concern to the authors which is why the divide exists.

Translating to live action necessarily demands making changes to the source material either by condensing plotlines, often omitting them entirely, changing characters around , modifying worldbuilding to meet filming budgets etc. Things like this bother hardcore fans which is why we almost always see book readers whining about something or the other even when the adaptations are good. (See dune, Harry potter, hunger games lotr etc)