Missiles both have bigger bursts and longer ranges than HMGs and similar weapons, for none of the flux cost. I think that limited ammo is one of just two main downsides of vanilla missiles compared to other weapons. (Excepting Pilums and Salamanders) The other downside is that they can be intercepted with PD. But on the rest... They have amazing range. They cost no flux. They're guided. While you have ammo, they have insane DPS. Look at the Harpoon rack. If you had unlimited missile ammo without changing anything else, it has 750 DPS in a small slot. That's THREE Hellbores, with over twice the base range.
Why in the world would you think people just want regenerating missiles to be the ammo number deleted from the spreadsheet? Of course they'd be insane if they could fire at their current DPS with unlimited ammo. Nobody is suggesting that, because it's bananas. Regenerating missiles would need to be properly balanced - but then, missiles in general need to be properly balanced anyway. Many of them are bad, and some them are way too good, even in their current ammo-limited state. Might as well make them a proper pyramidion in the weapon triangle by giving them regen while you're doing a necessary balance overhaul.
I can't really think of any bad vanilla missiles...
-Harpoons are easily stackable assault damage on overloaded or vulnerable targets
-Sabots are a meme they're WAY too powerful.
-Swarmers are sustainable damage for several minutes worth of fighting, and help fight fighters - a BIG DEAL.
-Annihilators are the same way but trading the guiding system for more damage and faster speed.
-Hammers are like sniping torpedos, doing a lot of damage and flying particularly fast. Extra shot too!
-Reapers kill things. They kill them dead and once they die they are no longer alive.
-Atropos are guided torpedos. Not great guidance, not reaper tier damage, but it's quite a lot and it hurts.
-Salamanders mess with the AI, deal EMP damage (often focused on the engines) and are infinite ammo, which is a big deal.
-Proximity mines basically make fighters irrelevant and act as a wall of PD, with enough ammo to last a while.
-Pilums, enmasse; confuse the AI, force them to keep shields up, completely disarm phase ships, and occasionally even finish overloaded targets (especially in tandem with salamanders disabling engines!)
-Hurricane is antifighter or anti everything else, with enough damage to one hit many ships. Plus, the MIRV means it can avoid PD if it gets within burst range.
-Squalls are sustained KE damage, something incredibly effective at pressuring ships at extreme ranges and opening them up for followup attacks.
-Locusts are probably the most powerful missile in the game, to be honest, the launcher fires so many of them in such a fast rate that enemy ships refuse to drop shield if they are unfortunate enough to drop their shields. This often means that locusts combine with kinetic and energy weapons to very cleanly force ships to be overloaded from long ranges, and then things like harpoons or other means of assault damage can finish the vulnerable enemy.
Missiles rule.