Yeah, I wasn't clear - I'm with you on both counts. Though, to be fair, it really could have gone that way with Tangerine Dream or someone doing the music. I mean, consider Blade Runner with its synth heavy vibe... I wonder if that could have worked for Alien?
Maybe not - synth-wave is having something of a renaissance, I think, but if you listen to many the soundtracks of many of these old movies with this kind music, they date fairly quickly... Carpenter and Vangellis being stand outs that don't of course.