Here is one. I see Di2 the same way I saw Gibson's Robot Guitar that came out. It was a guitar with small motors in it that tuned the strings automatically. Sure it is kinda cool, but it is entirely unnecessary, with a cost that is not worth the benefit. For the uniformed, tuning your strings on a guitar is something you do nearly every time you pick it up, it is as regular s switching gears on a bike. Disclaimer, I am not a racer, and I still use a friction shifter.
Also, if you want to look for innovation, Runner1 pointed us in the right direction. Look at any HPV team. I was in the robotics team in college, and we shared a work area with the HPV team. They hand make recumbents with a little material as possible and make a custom carbon fairing. They have a speed trial one that is longer and has maxed out somewhere around 63-64MPH, and the regular one they race in ASME challenges.
http://humanpowered.mst.edu/photos/2010/west/12.jpg
That was from 2010, when they won every ASME category for both east and west coast competitions. (Design, Male Sprint, Female Sprint, Endurance, and Overall)