Have you considered other portals besides Steam? It would definitely be the best to get your game onto, but Desura and Good old Games might offer you a spot. Of course, I don't actually know if either of those have ever taken visual novels before. They may just think there isn't enough interest in t...
I'm surprised you have to go through greenlight to get your game on there. I had assumed that whenever someone successfully gets a game on Steam you develop a sort of rep with them. They know you produce quality work, so they personally look at what you send through instead of relying on greenlight....