Most Hollywood sci-fi is crap yes. Even the films that are good (Donnie Darko, Dark City, RoboCop) are highly derivative or tongue-in-cheek mockery. But like Waz said, it's not just sci fi but a general movement by the industry towards recycling old ideas into the same old crap just with different packaging (and even that doesn't change too much). STALE STALE STALE.
Anyone here seen that MPAA anti-piracy commercial that they play before the previews in movie theatres? It's got some set painter guy whining about how he struggles to put together 12 jobs a year in order to keep food on the table, and piracy affects him more than it does the multi-millionaire studio heads (which is bullshit because he gets paid the same amount whether the film makes money or not, but that's another issue altogether).
Any way, that commercial sparked a little conversation in the one course I'm taking right now ("The Cinema") about how the major studios are just assembly-line factories. Think about it, you have hundreds of people who do one job over and over and over (build sets, paint sets, operate cameras, write scripts, act, etc). How can you say that that's not an assembly line? I mean for fuck's sake, there are people whose only job is to adjust the camera's focus. That's it. That's all they do, pull the focus when the director or cameraman or dp wants to move the focus from one distance to another.