Lord of the Rings spoilers?
Was CGI mocap Gollum groundbreaking at the time? I remember hearing that somewhere.
I just think that the pratical effect Gollum is so much better.
I watched all of the extended editions of LotR one or two months ago, and the beginning of Return of the King paints Smeagol's downward spiral into Gollum beautifully. I really got the sense that Gollum was a victim, and he looked utterly horrifying crawling around with practical effects. He was absolutely wretched.
Then we go back to CGI Gollum and it doesn't even feel like the same character. Imagine if you replaced the CGI Gollum with the PE Gollum in every scene in the movie. It is a whole lot creepier. The thought of seeing the PE Gollum scuttle around for a third of the screen time or whatever and seeing him smile and sing would be a lot more impactful. And Frodo's reactions to Gollum such as grimacing at the sight of him would feel realer.
And before you say "CGI Gollum is a more accurate portrayal of Gollum", let me remind you that the Uruks look nothing like they do in the books. The PE Gollum fits in way more with Peter Jackson's representation of Orcs and overall aesthetic in general.
PS. I don't hate CGI. CGI is good in plenty of movies. Gollum just doesn't fit here with the art design of the rest of the film.
The PE one evokes a sense of disgust to me.
Here is the part of the film showing Smeagol metamorphasize into Gollum if you haven't seen it and want to.