My fleet have always be coward, so I have just buy carrier or gryphon!
I see always when I fight, my fleet around of the map on group, never separate, never between two ennemis. So, I loose very not many ships with that.
For me, i prefer a AI coward of lose ship where I need to re-approach my strategy and keep to go on the fleet ennemi than a stupid AI who do not value the ship than you have give him.
The only ship than I have lose in a game, this is my ship, for say. And each coward of my fleet have kill more ships than me.(except on pursuit, because they are too slow)
I can understand on early game, but on end-game, you love this coward!