It's not that VNs are necessarily a niche thing because they are Japanese or developed by lesser known companies (here), it's because mechanically they are no more than a very long cut scene. Calling them games is a bit of a stretch, their more like books that you click through on a computer or console with a choice springing up on occasion. Manga Gamer is the only company I've seen that has really tried to market VNs in English and they aren't doing so great. They claim it's because of pirates, but I bet even the people who would want to buy the Higurashi VN might be turned away by a $50 USD price tag.