Coming from a background of surfing, I learned that the surfboard should be light. I often wondered, "if a surfboard is eight pounds, and it takes a lot of effort to make one two pounds lighter wouldn't it be easier to just lose two pounds from my body?" But it doesn't work that way. The board needs to be light to turn easier and be more responsive.
The same applies to bikes. Don't mess with the bike. That's me, of course. To each his own, but my ride has a lot of strange twists and turns, and even five pounds on the back over the wheel messes me up. Bikes aren't meant to have that rack on the back. It completely throws me off.
I wear a backpack. But to each his own.