No matter how futuristic sci-fi movies are supposed to be, something always dates them

I'm well overdue for a post here, so I'm going to offer up a profound observation.

No matter how futuristic a sci-fi movie or TV show is, they're always somehow dated by the era it was created in.

Although this is nothing new, it really hit me while watching Star Trek IV the other day (a movie I TiVo'd since I haven't seen it in its entirety since it was released). It didn't matter if they were in the 23rd, 24th, or 80th century. Shatner's toupee and Catherine Hicks' hairstyles were pure 80's. And if you go back to the beginning of Star Trek and look at the episodes...particularly the "hippie" episode, you realize it's a parallel time line. It's like at some point in the future, history will repeat itself chronologically in the form of bad culture and bad hair.

Other examples off the top of my head:

• Mark Hamill's hair in Star Wars. Fortunately, no known culture had Princess Leia's "cinnamon bun" hairstyle, so I can give them a flyer on that one.
• Logan's Run. Were we supposed to be doomed to wear bad, oddly striped jumpsuits in the late 90's?
  
• Buck Rogers in the 25th Century. Please, PLEASE tell me that Earth will not be once again populated by a society that finds disco roller-skating entertaining. I mean, seriously, I swear these horrible scenes are why you don't see this show in syndication.