It definitely does make the basics go out the window, but that's why our military training regimen requires attention to iron sight proficiency too. Iron sights generally don't break, whereas optics like to quit working at the worst possible time.

That speed is also the advantage, and it makes a huge difference, especially with shooting on the move, or firing around weird shaped barriers. I loved how much faster on target the M68 made me in basic. I could be more precise with the iron sights, but man did it knock down those pop up targets quick.