Don't think you did anything wrong it is just not a very memorable scene and there were much better images.
I also think no border would be better. In one way it may all be a bit to clinical .
Bob
First off, I love these lighthouses and especially your composition and delivery of these shots. The lines are excellent, and the low angle light to add shadows works great.
With that said, I see a couple things that probably cost you (I didn't vote on this challenge so I can't tell you how I felt at the time).
I understand why you interpreted your composition as 'off centered', with the light at the end being your subject. However, for the viewer, I think the subject is the entire pier and light, so in many ways, it is mostly centered, albeit riding across the image rather than dead center. In fact, the focus point is dead straight ahead rather than the light which is slightly out of focus due to the DOF.
In addition, the clear blue cloudless sky is working against you where the sky adds almost nothing to the image.
Finally, I think the strong border (the white line framing the thick black border) makes the frame look very think and overwhelming.
It is a very good solid shot, but it actually isn't your best work on these lights.