I said the same thing about clipless pedals. "I know how to flip a pedal and reach down to tighten a strap. And I don't have to have matching pedals and cleats!" Rode my toe clips and straps till 1995, or about 10 years after clipless was first introduced. Now I ride nothing but clipless, even on my fixie.

I said the same thing about indexed shifting. "I know how to shift gears and center the derailleurs on a bike! I don't need some idiot-proof shifting system". Rode my barcons and down tube shifters until 2005, or about 10 - 15 years after successful brifters were available, (depending on whether you count Shimano's RSX stuff).

I got out of the bicycle biz in 1986 after 15 years, but several of my friends stayed in. Those friends would listen to me mock "the latest iteration of Shimano's failed indexed shifting" and they would tell me, "Just go ride it." I finally did, and now I ride nothing but brifters of some flavor or other.

Today I count those two innovations as a couple of the biggest conveniences in modern cycling. So I'm not so quick to poo-poo new gear as it gets introduced. Plus, I have ridden Di2, and it was impressive! As several have said, no more rubbing front derailleurs. No more lagging front downshifts because the derailleur return spring can't overcome the force you're putting into the chain. No more having to coordinate "easing up" to facilitate a shift in the middle of a climb because you overestimated which chainring would be necessary. Just hit the button, it shifts. Period.

So, I would say to you, "Just go ride it".