One day, Avatar will be like that. When the effects grow old there's nothing underneath it to make it good, as it were.
The original Jurassic Park (and Lost World to some extent) is still regarded as a technical masterpiece, especially since it's Dinosaur animatronics are pretty top notch. There was no flashy CGI, just pure mechanical work.
The script may be a bit tacky nowadays, but I still get goosebumps whenever John Hammond says "Welcome to Jurassic Park" with the Brachiossaurases in the background.
Now, if we're talking about Jurassic Park III, I fully agree with you. A CGI crap-fest and with a forced plot just to get the character of Alan Grant back in the series.
Yeah, the first one is still amazing. I re-watched all of them earlier actually. It's a techincal marvel for the time, akin to Mario 64 in the gaming world.
2nd one? Alright at the time, but it doesn't hold up now.
3rd one? IT NEVER HAPPENED.