I love when authors get hooked on their own characters by writing not-tacky sequels (especially when the sequels have titles entirely different from the original). Take Louisa May Alcott, for example -- she loved Jo March so much she kept returning to her. Or Judy Blume's Fudge. Or L.M. Montgomery's Anne.
If done well, it speaks to good writing. It's not cutting and pasting the exact same intro to every story, but rather exploring the development of a character as if the character were a child the author wants to watch grow up.