The point of video game development is to produce a video game for people to play. It is not to make video games as expensive as possible and create a maximum amount of make-work, employing as many people as possible.

Otherwise, heck, go build models for areas that one never actually sees, because that would require more modeling work. Build the sets in reality and record sound on them, because that would require construction workers. Disallow the graphic artists from using computers to do their work, because it requires more graphic artist work to create the artwork using only pre-computer techniques. There are an infinite number of ways to generate greater labor requirements in making a game; there’s nothing unique about synthesis of a character’s voice. The game might cost thousands of dollars a copy, but its creation would, no doubt, employ a great many people.