A study that verifies which part of what I said exactly? That a lot of people can't see the 3D? About 25% can't from what I remember I read somewhere, gonna have to look it up and I'm too lazy
If it's the eye-strain, there's not a study on the 3DS exactly, but on the 3D technology it uses. It was phased out for a reason, despite being popular around 2008, meaning the eye-strain was reason enough for other devices to fail. Then again, at that time a lot of people had bigger issues than to pay attention to eyesight, so that might have been it...
What are you referring to exactly when you say "most of the 3DS library"? Because hardly 15% of all 3DS games (including indies, it's around 40% without them) use the 3D and most of those only use it for just a tiny part of the game (eg: Pokemon XY pretty much only use the 3D when encountering Xerneas/Yveltal).