My reasoning is that on a typical commute, you spend very little time shifting versus a lot of time pushing the pedals and the wind. And when you hit your limits, of power or fatigue, it's not because your shifters wore you out.
Typical commute, huh? Whatever... We all ride differently, of necessity or preference. We all spend more time pedaling than shifting because it cannot be any other way, so that's not saying anything, is it? I guess that what you're really saying is that YOU don't shift often and don't think shifting is an important part of how you ride. For me, it's the opposite; I do shift often and shifting ease, quality, and speed are all important to how I ride. I told you before that I ride aggressively and fast, and in order to do that, I need to shift frequently, because my urban commute has lots of rolling terrain, stops, and slows, so when it comes to carrying speed and accelerating, I employ gears to get there quickly and efficiently. Using gears (i.e. shifting) is precisely what allows riders to do more work more efficiently without hitting your limits.
Some prefer drop bars and some prefer flat bars, I've commuted on both. Whichever you prefer, they are very different. The drop bar puts your wrists in a different orientation (with the exception of the tops position); the range of different positions is wider (from high and back on the tops to low and forward on the drops); and on modern bikes, usually can be set up with a greater saddle to hands drop than flat bars (when in the drops ) and thus a flatter back/more aero position. If someone wants a drop bar bike, a flat bar bike is not real close to the target.
Listen, I objected to your claims that flat bars were uncomfortable, slow, and put the rider in a position very different from drop bars. Those things are not true.
I fully realize the bar types are different, and that there are more hand positions with drops, but those differences alone do not make the rider more aero. Getting aero is a setup issue, and I'd point to the fact that the most aero cyclists, and those most concerned with sustaining high speeds, do not use drop bars, namely Individual Pursuit and time trialists. No, they don't use flat bars either (though TT base bars and pursuit bars do look a lot like flat bars with bar ends), but then again, we're in the commuting forum, not the racer forum, so ultimate aero is really taking things a bit too far.
The simple fact is that a flatbar can be set plenty low enough to get a low/flat back riding position for most commuters, based on how I see most commuters riding. I simple scroll through the Commuter Bicycle Pics thread will give a pretty good cross section of that, and plainly most do not ride in anything of an aero position.
It's just plain misinformation to state that flat bars are uncomfortable, slow, and difficult to setup.