I don't know if my son would technically be considered a "transfer" or not. He, as a HS senior, had signed a LOI with one JUCO and shortly before his freshman year began, ended up requesting a release and signing a LOI with another school. He did so for a couple of reasons.
I can tell you from our experience, that this is a traumatic event in a kid's life. It is a decision that can be filled with guilt (for the coach and the players he feels he's letting down) and fear (am I doing the right thing).
The reasons that a kid decides to transfer are numerous. Just as the reasons for signing with a particular school are very individual, the reasons for leaving are as well.
I understand that a program can be hurt in several ways by a player leaving. I can also understand that a program and players can be hurt by a coach deciding to leave. I can only respect a coach that makes it possible for a player to make a change that he and parents feel like he needs to make. For a player to stay where he doesn't want to be (due to whatever reason) can never be a win/win. Changes happen in life and there's no reason to make things more difficult for anyone. Whether that's the coach or the player.