Counterpoint - the benefits of wireless are there but the worry of your unit dying in the middle of a ride now replaces the concern of whether your derailleur is tuned and ready to go. It's easy for a shop to assemble, but now I'm worried about shorting the control unit of my di2 which would be a pricey fix. I have two bikes: one with and one without di2. Both work just as well and one costs much more.
I do love disc brakes though.