Game studios claim that the reason they don’t release any information is because they don’t want the actors to leak the game in development, but in my opinion this is just an excuse, have them sign an NDA.

What BS! Actors sign NDAs for movies and commercials, so if movie or television plot points aren't regularly leaked, then why would video games be? You're right, this is just an excuse. I think these videogame voice actors are perfectly justified in their effort to have better compensation.