Nah. Luigi had a personality prior to the 3D era. His modern portrayal is, at bare minimum, inspired by the Super Mario Adventure comics, where he was portrayed as the more cowardly of the two brothers. And that’s not even looking into things like the Super Show, which created Toad’s modern voice or the CYOA novels.
He put a voice to that persona, but he didn’t create it whole cloth.
Inside America’s First High Speed Rail (www.youtube.com)
Video message from Shigeru Miyamoto and Charles Martinet regarding the change of Mario’s voice actor, announced on 21/08. (twitter.com)