What if, for instance, squid were forced to operate during daylight hours (change of environment). After a bit, the squids eye would come to adapt to daylight existence. The reason these critters' eyes are perfect for their particular existences is that millions of years of environmental pressure and experimentation have hit upon the current setup. What these critters have now, however, may not be what their particular descendents need; there will be environmental pressures to change the way they look at the world (pun intended).
BTW, human eyes are not as suitable as you claim. Our ancestors did a lot of hunting and were constantly on the lookout for predators; their distance vision (and ours) was much more acute than their near vision. However, civilized man does more work up close to his eyes, and has little need for distance vision. Think about this as an environmental pressure.
Again, a nice story. But where are the transitional fossils? As time goes on, the fossil record looks even worse for microevolution than it did during Darwin's time. Besides being "gappy," you have the problem of unevolved, "living fossils" like the coelecanth and the horseshoe crab.