As one of those trying to keep things away from the paying dps for durability, the biggest reason it does not work is that as you get into the late game and the AI planets have a lot of units, any unit, even a high mark starship, has a low life expectancy.
That's the biggest reason fleet ships win in the late game, I can send a couple hundred fleet ships in and have them die like flies, but output decent damage.
Or I can send in a few starships that don't die quite as quick individually but their damage output sucks.
For now, we'll see how this new balance on them works out.
D.