I think it’s more about the business need rather than the art. Many blockbusters these days are in a pretty extreme crunch. The business “can’t afford” to release late, and there’s so much CGI that everything needs to get done as quickly as possible.

I’m sure many (most?) CGI artists would enjoy taking more time, but the business need (and their need for a job) trumps that. You can draw parallels to software development there too