I think Nintendo has made a few missteps with the 3DS.
They should have included the second analog slider in the initial design of the 3DS; especially after hearing 7 years of PSP owners/developers/etc. complain about only having one slider.
Though, the true blunder is that Nintendo explicitly stated at E3 2010 that they opted to make the top screen 3D (and larger than the bottom screen) INSTEAD of a touchscreen.
At a hardware design level, they literally chose altered visuals over enhancing gameplay inputs (which also runs the batter dry faster); this was the most common, yet intuitive mistake DS owners made (they think both screens are touch input capable since the bottom one is) because it naturally makes sense that it should be; the screens looks the same so they should function the same.
This also would have allowed Nintendo to better differentiate their product from the tons of other hardware (now present in the market) that has single touchscreen gaming.
