Compounding this is nowadays some investors and publishers expect you to have a Steam page already when you're pitching. Seeing that wishlist trend is one of several ways that they seek to identify and minimise risk.
Tommy Thompson
anyway I have a theory: the reason most indie devs are so obsessed with wishlists now is because we have reached a point where steam is a self-reinforcing arbiter of what people notice. Wishlists get you ranking on new and popular and in nextfests. Streamers watch those and play the top games.