Web developers (yes, even LDS Web developers) need to be concerned with how usable their sites are. Key to that consideration is designing your site with a purpose in mind. Sites that try to be all things to all people rarely succeed. The correlary to that truism is that if you can design your site so it is more targeted–more focused on achieving a specific purpose–the more chance you have of achieving that purpose.
I read a great article in this regard the other day entitled Flywheels, Kinetic Energy, and Friction.
Let me know what you think.