It's a little more nuanced than that, I think.
Let's go with the hypothetical scenario that Bayonetta made 450 Million USD, right? If we take certain factors into account (Region pricing, discount on sales, etc) and the fact that there are only two games in the franchise, that would put the sales somewhere between 10 million and 15 million copies. For reference: That is Halo 1 - Halo 2 levels of success we're talking about.
That is a huge audience for a franchise, and when your audience is that big, you can't rule out that the voice acting can be important to a certain part of your audience. This also opens up all sorts of other opportunities: Spin offs, merchandising. Licensing. It makes sense to invest in the face of the game, which is the main character and voice acting is an essential characteristic. To use an extreme example: People don't purchase a Mario game for its voice acting, but you can bet that Martinet is paid millions for his performances, even when they are often little more than yelps.
Well, Bayonetta sold a lot less than that, but ok, let's say it did.
There is plenty of games that sold over 10 million where voice acting is worth very little. Where the big bucks come from, is how famous the actors are and how they levy that.
People like Charles Marinet and Troy Baker are worth millions but they are not only selling their voices, but also their fame and name. Having Troy Baker as Joel is a prestige thing. Charles Marinet voiced countless Nintendo characters for 30 years, just having him say WOOO is like a tradition.
I did a quick search and it seems Nolan North is worth 2 million, Troy Baker is worth 6 million, and Charles Marinet is worth 10 million. (don't trust these shit ass google numbers though, but still.)
2 games in the Bayonetta franchises, even if they sold 15 million copies, can never match that. She just doesn't have the name or career to be worth that. Maybe if she worked in the industry for 20 years, and her name was known by all, but it just isn't. It's a niche game and a talented but obscure voice actress, no matter the game sales.