Lateral line = fish's ear. Plugs that make sound/vibrations in the water that fish can "hear".
I think eyes really depends on the plug, the bait it imitates, and how its used. Most of our bait down here have very prominant eyes. For a plug, like a metal lip, that is worked slowly, the eyes can be important cause they are visible. If nothing else, they give me a little more confidence in a plug. Sometimes, its that added confidence that can turn a good plug into a great plug
Jigman