Well...Robin didn't come around until much later than those two, so that's a bad example.
Not at all. Not one in one hundred thousand people who recognize Batman or Superman knows anything about the early history of the comics, so the importance (or lack of same) of featuring particular long-standing characters has nothing to do with when they were introduced.
Peter Parker being in love from early adolescence on with his next-door neighbor Mary Jane Watson in the Spider-Man
movies didn't appear to have cost the studio a single ticket sale...