It's also what you want out of your bike. For some, riding it is only a piece of the equation - building it is another and important piece.
I mentioned before that with cars, I tend to buy only as much wiring harness as I need, and then build from there. My desired combination of addons isn't usually in the factory option package, and a lot of times, I am looking for something that is really outside of the envelope. So "farkling" is the only way to get what I want. No crime in that! Same with bikes - why come down on someone who chooses to build what they want, instead of figthing an endless battle with the manufacturer to convince them to build what might likely be a one-off?
The build is part of the journey.