Sci-Fi movies tend be more expensive to produce than dramas or documentaries because of their special effects budgets as well. That's probably why they tend to suffer from "squealitis" than other genres, because the big movie houses are afraid to gamble a 100 million dollars on an untested concept.
That's why we should be rooting for more original movie content from the likes of Netflix and Amazon. They seem to be be making riskier bets with their content, and making far more of them. Sure, some of them suck, but they have both had a few good hits recently.