I think it is partly the audience to blame and the people who run the company that is at fault here. This show is a perfect example. Defiance is pure crap. I know it,you know it but see how many people have supported this show and the game? I'll give you another example. We all know that MTV/VH1 stinks but if you see how much rating Love Hip-hop Atlanta pulls, it's no wonder why it's still on air despite having no meaningful content.
http://en.wikipedia.org/wiki/Love_&_Hip_Hop:_Atlanta
This show rakes in 2-4 million viewers each week. Yeah, cringeworthy stuff
Remember, everything these days is about profits and maximising profit; with minimal risks. No one is willing to take a huge risk on a new concept because of it's uncertainty factor.
Sci-fi in the bigscreen is a different story. It's not hard-SciFi that we all adore and love but a diluted version off sci-fi. This is so that the general audience can understand what the hell is going on while also enjoying the movie. All the masses want to see is explosion and more explosions.Put in sex scene in it and that's a cherry on cake.