For me it has to do with branding. I don't want proprietary parts on my bike. I also don't want parts made by another manufacturer but with in this case a Trek/Bontrager name on it. If the headset on that bike is made by Tange for example, then it needs to have the Tange logo on it or nothing at all. Not a Trek, or a Bontrager logo. I don't want something like a Giro helmet or pair of shoes that's labeled as a Trek/Bontrager. Same for other accessories. If a blinky light is "manufactured for Trek/Bontrager" by Cygolite, even if they come out of the same plant/on the same assembly line, I want Cygolite on that light. It's a bike light. Cygolite makes bike lights, not bicycles. The last thing I want is to be dependent on that/those stores/brands and their lack of choices for my purchasing needs. Don't get me started on Nike.