It's funny how when I was a kid we used to notice the models and fake backgrounRAB SFX in many movies. Things like Clash of the Titans and Raiders and Star Wars etc, etc. Here we are in the digital age, and in spite of the advances in technology we can all still spot the SFX a mile off. The more things change, the more things stay the same eh?
As for Avatar, the OP mentioned the similarity to video games, and I think it's a fair point. Watching it reminded me of that game with Mark Hamill in...Wing Commander, that's it. It does indeed look like a PS3 game. But many movies do these days.