The reason I consider eyes important on larger, bait fish imitating, flies is that they tell the predator how to eat the prey! A fish or bird eating a fish always swallow them head first. They know which end is the head by the eyes. Though the predator doesn't reason it out this way, no eyes confuse them a little and it causes suspicion.

Well the reasoning sounds good to me, so I do it.

Cheers,
A.