The fix is rather easy actually.
You cap each ship roles size, then make each successive size ship exponentially more expensive.
So if we compare a frigate to a cruiser:
Frigate is size 230 at cost factor x 2, where a Cruiser could be size factor 920 at cost factor x 8. That way the cruiser is 4 times as powerful, but at 8 times the cost...you'd still want to build a few to counter larger enemy ships, but you'd also build a lot more frigates due to their lower cost.
The problem is..., like the other 4x game, that when you have research cruiser; destroyer and Frigate role in military will be void. You will tend to use the bigger ship as your main military combat ship.
It is also true to Distant World. I saw somebody show his / her ship design (fast ship, fire ship, etc) that have 800 size (rather than 150 or 200 ship size).
The reason is simple, Shield and the 360 degree weapon fire.
In real world, big ships always require escort. Because whatever they do, or whatever equipment they have, big ships always considered as easy target by the enemy. Thick armor can't help the ship to survive torpedo / missile attacks alone. But because of "Shield feature" in most 4x games, this problem become void. Big ship can always bully small ships. They can even single-handedly destroy a squadron of small ships without the help of escorts.
I'm not against shield feature. But, in most 4x games, shield is not considered as a kind of force field. It require no power to maxed it's potential capability. So... Shield is... and always is considered as an armor that has big HP. Plus, maneuverability of your ships won't effect the targeting ability of the opponent, thus make the need of fast / high maneuverable ship need become void.
So, what about this idea (I don't know if it's work or not) : When a ship is not in combat, it's shield will work only at 1/4 power, and need the usual constant power like usual. But when it go to combat, it will take the free power from reactor to maximize it's shield potential. If by then the reactor lacks of power to empower all of it's combat feature (weapon, speed, and shield), then only of one them that can be activated (well, weapon always go first, so, you have two choice. To balance the number of weapon and shield of your ship or you get only 1/4 of your shield power.
To limit the number of reactor for a starship, you can always increase the need of fuel for each reactor and add the weight for it.
< Message edited by Brainsucker -- 1/16/2012 4:37:16 AM >