As others have said, red dots on pistols can work very well, but you need a quality optic and you need to train with it. An optic does not just automatically improve your target acquisition but it CAN be faster and more accurate once you know how to use it.
I try to buy optics ready pistols, but not always. Depends on the purpose of the gun. I believe optics is the way of the future, but for now I am better with iron sights even though I have started to practice regularly with an optic.