The relative parity of the 80s and 90s that you rightly cite, Aniket, is what makes the Big Three so improbable and incredible. What you describe is the "norm" in tennis, and partly why the Big Three, Serena, Steffi Graf, and Tiger Woods in golf, were exceptional and amazing.
Not having had one GREAT success in life but many smaller ones, I can't argue with you about the sufficiency of such a thing. I'm much more familiar with the idea that one great success, especially early, especially in sports, can result in the sense that "everything after savors of anticlimax," as Fitzgerald wrote of Tom Buchanan in The Great Gatsby. I don't think Andy Roddick was happy with 1 slam because he lost to Federer in so many finals, but I'm sure that many of the others felt that it was the pinnacle of their career and felt complete satisfaction. I simply don't know.
It seems incredibly difficult in the current environment for a player ranked outside the top 10 to string together 7 matches, and that was more or less the focus of this piece. Of course they still play, and they still win, and they still dream and train and try their best. I've simply paid more attention to them of late, and tried to draw more attention to them in this piece.
Thanks for reading and responding, my friend.