"As an interceptor, it fails by having a short range, low speed and only one hardpoint. As a transporter, it is unable to carry Heavy Weapons Platforms and only has room for a small squadron of soldiers. These are the main reasons why a number of X-COM Commanders frown on the usage of the Lightning. "
https://www.ufopaedia.org/index.php/Lightning
One weapon, limited troops,
high speed.
IMO, it’s supposed to be a scout-killer. In which role its limited range may be the worst flaw, the rest is acceptable. The enemy crew is also small.
You don’t really need fire support as much as scouting before Motion Detector stage, so it would still do better in a mod with small vehicles, just to fix the “walk out of the door, die” problem and scout around a bit.