Unfortunately it's not laser's stats themselves that are bad, those are actually average to decent. It's a combination of indirect factors that make lasers "bad".
1: Alternate Ammunition
Non-pierce type ammo existing for a wide variety of weapons, hems in on lasers largest advantage of being good against otherwise high resist foes. Given the variance of the tech tree/spawns you are significantly more likely to have multiple alternate ammo types before you have lasers. Hell the sheer variety of damage types and methods of delivery makes lasers plain and uninteresting.
2: Damage Calculation
Due to the order of operations for damage calculation, lower end values of penetration are not equivalent to higher raw damage. Raw damage is the single most influential factor on the attacker odds to deal damage. Armor penetration is also a percentile modifier so varies in effect with targets armor value. 33% on 10 armor is only a difference of 3 points of damage. Penetration does mean more as armor rises, but around ~60-70, the lack of base damage means you have an uncomfortable chance(20-60% depending on weapon) to do nothing because 0-200% dmg rolls for shooting.
3: Secondary features
Lasers largely lack any secondary features. Conventional weapons often have buttstrikes for melee situations so you can forgo equipping a melee weapon. Chem, plasma and some conventional weapons strip armor before armor penetration step so they still do something even you whiff on the dmg all the way down to 1%. Even claiming penetration as laser's feature is dubious with 15% on rifles and 20% on snipers. Oh and penetration on rocket type weapons.
4: Access
The best laser options are gated behind really sucky optional content. Either the eurosyndicate deal with 1500-800 negative score at best(per month potentially YMMV) and massive purchase/operation costs, or Russian files which without cheesing is about equivalent to a merc battleship subbing lasers/gauss for plasma. Getting "good" lasers in the first case is a death sentence if mishandled, and expensive even if managed properly. The second case is better but you still probably can't pull it off in time for the rewards to offer much utility, given point 1 above.
