I think the best way for this to work is for each ship to have limited amount of power that is can use for it's weapons and based on the type of ship you have would determine how many launchers and energy weapons slots you can use. Now the best way to limit how many or how strong a weapon is by how much power that weapon uses in it's slot therefore this would allow the player to base his/her weapon on how they play not how many weapons slots each tier gives you
so if you want high-end phaser array you might have to get low-end launcher and vise-versa
Now this wouldn't change the way the game play to much but it would allow the player more customization options and would make space combat a little more tatical
they kinda have in a way...weapon power goes down when shooting, and this is why most tacs dont use all dual cannons.
dual cannons shoot more, and therefore need more power then dual heavy cannons. They shoot more and thus they can proc more often and get crits more often, but the power drain comes into effect and then theystart to do less dmg.
This is not a complete pros and cons of the weapons by any means, but we do see powerconsumption here in effect. and would be why some people like havinga beam bank on thier ship...im all for cannons on tacs but some people still use the dual beam banks...