Supposedly, translating these games has created problems. After Taimanin Asagi was translated and sold on steam, someone found out that Sakura was explicitly 16 years old. This is a problem because that means she's a minor while she's being raped on-screen. Steam pulled the game within 24 hours, I think it was 16 hours. There are other games that companies have tried to translate and sell officially, and the material in the games were found to be too extreme for western audiences, leading to international backlash, including calls for censorship and bans. It's also very difficult to defend (from a western point of view) because most of these games are not really about creating "great" art, they're for masturbation.
Japanese companies often choose not to do official translations because they feel that it would create more problems than profit. Supposedly.