My first point was that before everything was made by hand, the scenery, settings and everything. The first computer generated effects were horrible because technology is an ever improving thing. And the thing about older Sci-fi is that the ideas were there.
It's like @PostIronic and I discussed once, there was something in the water then. Call it hallucinogenic drugs, the moon landing or whatever, in that time period and that time period alone people in art were open to ideas we've had never thought before and probably wont again. Even the somewhat bad-looking Sci-fi movies of the era had character and such unparalleled imagination. Nowadays there's nothing that even tries to think outside the box in the genre, it's action minded, explosions and CGI. Bear in mind i haven't watched Interstellar yet.
And yes, for the reason, Alien is a sci-fi masterpiece.
I think I've said it in this thread before, but I'm not even a big Alien fan, but I do recognize the film is a Sci-fi masterpiece. There are quite a number of incredibly dated looking films from that 60s and 70s era in the sci-fi realm, but one things they do have is originality, imagination, fascinating characters, and ideas that are actually interesting if one strips away all else. Today, we're dazzled by CGI and FX and for the most part seem willing to overlook the shit that tries to pass for a storyline underneath, and the half-baked plots and ideas used. The less said about dialogue, the better.
That period was home to such fascinating movements in the arts. The New Wave/Nouvelle Vague movements in film in that era were fascinating. The French with Godard, Truffaut, Resnais, etc; the Japanese with Oshima, Imamura, Teshigahara, etc; the Czechs with Jires, Nemec, Svankmajer, etc; New Hollywood with its plethora of good directors.
I don't think Hollywood has ever seen such a innovative and progressive era as that late 1960s to early 1980s New Hollywood era. So many brilliant young directors. And mostly working within the studio system. The major studios gave them freedom and creative license in an effort to resonate with the young people of the day, they overlooked the censorship model, and heavily stripped down studio cuts/ censorship of films, they allowed the transgressive to enter the cinema again for the first time since basically German Expressionism. And it's magnificent to see what followed from it.
And then Heaven's Gate happened. The knee-jerk was ridiculous. The fact it almost drove a major studio out of business was considered justification. But if you watch the Director's Cut released in 2013, at 216 minutes, as opposed to the original 150 minute clipped together highlight version of the film that a retarded studio and nervous producers insisted upon, it's night and day. That studio deserved bankruptcy for destroying Cimino's vision of the film and butchering it with that heavily cut release. Even worse, in so doing they ended an entire era of progressive and innovative filmmaking in the Hollywood studio system, and destroyed Cimino's and Kristofferson's careers, and almost managed to do the same with Bridges.
The full director's cut is a brilliant film and a masterpiece of the Western Epic genre. Here's a good read on it.
http://www.ft.com/cms/s/2/9a7d72e0-f8fd-11e2-86e1-00144feabdc0.html#slide0