If this were the case, then all modern humans would have what you call "good eyesight". Predation hasn't been an issue for humans for only a few thousand years, which is not generally enough for a trait like bad eyesight to diffuse into society if it were previously under selective pressure.

For instance, modern (and honestly eve ancient) humans have no need for the ability to wiggle their ears, but most people have the muscle and can be taught to use it. Non-human ancestors used this muscle to detect predators more accurately.

Additionally: strong acuity distance vision isn't what helps spot predators. Hearing, motion sensitivity, and color vision are way more effective in this regard. In fact, I'd wager that the invention of the bow actually increased the visual acuity of the human population, since ability to use a bow and thrown spear at long ranges was a heavily favorable trait for tens of thousands of years, and, critically, during the ice age, when natural selection was particularly heavy.