Crappy marketing. In my opinion, anyway.

Partly, I guess it's that Alexander McCall Smith is so over-rated.  So, he's written about a million books, and most of them haven't been published in the U.S.  Now that he's really popular (for some bizarre reason) everything he's ever published in the U.K. (it seems like, anyway) is being released here.  Practically all at once.  A veritable deluge of Alexander McCall Smith.

Even his fans will be sick of him.