The Rancor still looks great to this day. It will always look real. It’s the composited shots with Luke that have aged and will now always look fake for the rest of time. The original VFX in Star Wars and The Empire Strikes Back will never age. Some of the background shots and the unfreezing in Jedi will always have that 1980s look to them. Another reason why ROTJ is the weakest of the OT.
As for the rathtars, Tavor I think it was(?) hit on some excellent points. A lot of the monsters in the OT didn’t call attention to themselves. They were only shown partially and the sense of mystery and not knowing what the rest of them looks like allows the human mind to fill in the blanks. The filmmaker only has to give an outline of a monster, and let you, the viewer, make the rest of it look real in your mind.
I’m not opposed to CGI on principle…sometimes its done very well. But it’s rare. Usually it has that fake look to it, either the look or the movement, and it takes me out of the movie every time. Rathtars were horrible for that reason.
Second, and definitely the bigger reason why they sucked, was because it had that Men In Black gag feel to them. Whoever said that, wow, that’s a great analogy. The tone of that scene is not Star Wars. It’s wrong. The scene was a ripoff of the trash compactor scene in Star Wars, but think of the differences. The trash compactor scene looked and felt real. Luke nearly drowned. He came up from the water soaking wet, his hair a mess, spitting water and grime from his mouth. Then they all almost get smashed to death in a very tense moment.
The rathtar scene on the other hand, felt like a joke. A monster eats all the bad guys, but only drags around the good guy. It drags him around all over the ship, where he should be banging his head into metal at high speeds over and over again, but he doesn’t get hurt, he’s fine. There’s nothing real about it. No grit. It’s just a gag that belongs in a different kind of movie. The way Finn gets freed is similarly stupid and not Star Wars. It all has the look and feel of being fake, something that was created with computers and animations, and posed no real threat to our heroes. The whole scene only existed because it was a beat on a “copy Star Wars” check list that the filmmakers were trying to replicate.
One of the very few things in TFA which looked and felt bad. Most of the film looked great. My problems and criticisms had more to do with the plot.