Imagine if ammo could be bought in terms of “seconds of weapons fire”
If you only needed to use a little bit, it wouldn’t go to waste on missions that either immediately end as soon as you get there, or open space assignments where you may not even use any of it at all.
Each ammo cartridge manufactured could be worth, say, 300 seconds of continual weapons fire, so you can get more efficient use out of your specialized ammo.
You could easily have enough in reserves to last for extended missions as well, so you wouldn’t run out in the middle of one.
If you do run out of ammo, the weapons continue to work, but lose the bonuses.
Missiles used to be like this. You would buy one missile if you only wanted to use one. Or buy 6 if you wanted to use 6.
Ammo for weapons however is considerably different, and can’t easily be done like this without a whole lot of work and re-designing the whole ammo system.
Though he current system makes a whole lot more sense than the old system. You could find “ammo” items in loot after battle and each one would last forever without needing to buy more. This makes sense for laser lenses, but not for kinetic ammo or plasma charges.
Many players including myself have suggested weapons that use an actual ammo system, but it doesn’t look like that’ll be happening any time soon.