I seem to think that Cartoon Network modeled Rick from Rick And Morty after actor Peter Capaldi and it makes me think that Rick is drawn to look like Peter. Because if you look at Peter Capaldi and Rick you'll notice that Rick has Peter Capaldi's hairstyle and eyebrows and the same grumpy face as Peter Capaldi? Was Peter Capaldi used as inspiration for drawing Rick from Rick And Morty?
Bestie

Hi, Bestie! WOW! I think you are right! I wonder if the BBC k nows about this?
DTK

They are modeled after Doc and Marty from Back to the Future. The original Flash animation Justin Roiland created (Cartoon network/Adult Swim did not create the series) was even titled "The Adventures of Dock and Mardii" before being changed to Rick and Morty when Adult Swim picked it up (had to be changed for obvious copyright infringement reasons)