>>212458486
1. Most of those films came out at a time where "gritty realism" was the norm for American action movies and even ones with fantastical elements needed to have muted colors and conservative designs.
2. It was likely easier translate grey, smooth, vaguely humanoid, designs to CGI.
3. Those films in particular were either horror or leaning into horror and neither wanted or needed monsters with colorful or intricate designs
