Martin proved to be an essential character in Frasier’s character development. In Vanity Fair’s oral history of the series, writer/producer Lori Kirkland Baker said, “Martin’s presence, over the show’s duration, softened Frasier.”
Cheers also mentions that Frasier’s an only child, which was also retconned in Frasier with the introduction of Niles, played by David Hyde Pierce. Niles was created after the casting directors and writers fell in love with David.