To the Bolded part: 5.56 round AP does -15DT and .95 dmg. So you're removing 15 points of armor while doing 95% damage. Sure, against unarmored opponents it'll do less damage, but to anything with armor it will destroy. Totally worth it in every way.
Also, you can absolutely stockpile AP rounds- I have hundreds of 5.56 rounds, and a couple hundred .308 AP rounds in addition to hundreds of .308 JSP rounds.
Hell, right now all I'm using are hand loaded .308 JSP and AP, .44 SWC, and 10mm (smg) along with 20g magnum shot.
Ok, going over some numbers, let's have a Rifle and a Laser do 25 damage each. Against an enemy with 10 DT, they do 15 damage base, correct?
With the AP rounds, it goes like this
10DT: 25 - (25x.05) - (10-15) = 28.75
15:DT 25 - (25x.05) - (15-15) = 23.75
20:Dt: 25 - (25x.05) - (20-15) = 18.75
With Max Charge (MC) rounds, the Laser looks like this.
10: 25 + (25x.75) - 10 = 33.75
15: 25 + (25x.75) - 15 = 28.75
20: 25 + (25x.75) - 20= 23.75
The Laser gun actually does MORE damage than a regular gun with AP rounds does. If people are complaining about the Lase guns being weak, I can't help but wonder if they are even using the MC rounds.
Looking over a full list of weapons, I can see what some people are complaining about in a way. There are many more high damage guns for Guns than Energy, but the fact is that the guns still do roughly the same damage as their counterparts in each category, and Energy weapons with MC rounds scale much better than regular guns do (i.e., as they go up in damage, a Laser with MC rounds will keep doing more and more and more damage than a gun with AP rounds. In the example I used there is a 5 damage gap, but with 30 DAM weapons the gap becomes 9, etc.