Why Are So Many Marvel & DC Superhero Movie Costumes CGI?

CGI is used in Marvel Cinematic Universe and DC Universe films to create the fantastical nature needed for a superhero film, and that surprisingly extends to the hero suits the actors wear as well. From otherworldly villains to foreign planets in the galaxy, CGI is needed by the studios to translate the pages of a comic to the screen. The super-suits may seem like one of the few practical elements in productions dependent on CGI, but many of the suits in MCU and DCU films actually end up being largely or fully CGI.