Maybe if the shiptype stats could be upgraded to record damage as well as kills, it'd be easier to understand?
It's not that they're hard to understand. It's that they just don't do enough in combat. Little damage to many targets isn't as useful. Of corse it adds up over time but at that point the battle is already pretty much over. Aka they need to do more damage. Or they need to be as tanky as Armor Ships so they can just sit in middle of the enemy fleet and do their thing as long as there are no bombers (for Armor Ships) / Missile Frigates (for Electric Shuttles).
This is kind of same as high health low ship cap ships are (kind of) better than low health high ship cap ships.. or as railgun is (kind of) better than missile because railgun delivers the damage instantly which means the enemy ship might lose 1 or 2.. sometimes even 3 reloads.
The Electric Shuttle and Lightning Starship do a decent amount of damage, in line with other fleetships or starships.
1600 DPS is actually quite high - Bomber starships only do 1350 DPS. The ZDevestators are 1700 DPS, with a VERY restricted targeting capability.
Range isn't bad, either - 8,000 is higher than every starship except Zevas and Plasma Sieges (10,000).
The potential drawbacks are wastage, if there are fewer than 40 targets, and the inefficiency of distribution (which you were alluding to before).
However, because in AI War, the Average HP to Average Damage ratio is pretty skewed in favor of Average HP, lots of little hits do make a big difference. A quick check of common types gives a typical HP/Damage ratio of somewhere between 20-1 and 40-1. So those Lightning Starships are usually going to get a bunch of shots off - a 5 second reload is below average. If you have chance, try gaming it out with ilostit: 2 caps of Mk I fighters vs 2 caps of Mk I fighters plus a Mk I Lightning Starship. I think you'll be surprised at the difference the starship makes.
On the other hand, for a starship, they do have rather few HP (75,000 is less than half the Bomber Starship's 165,000 HP).
I also think Electric Shuttles and Lightning Turrets have far too long a reload time for them to be very useful, and they will usually waste it on the first single AI unit or two to enter range.
Personally, I'd love to see all these three Lightning AOE units given a reload time of 1 second, so they can act like limited range Attritioners. But I like Attritioners, so YMMV.