If anything, dumb fire rockets (I will use the therm missiles for seeker/guided ones since usually this is where the split happens in definition) should have a slightly faster flight speed and the rate of fire could be increased by a bit since they're hard to aim against moving targets and you also have to counter their placement on ship when aiming.
But they should and could be used as their real world analogues : a ground-focused weapon system to attack and defeat troops, vehicles, ground defense etc as they're used on attack helicopters and strike fighters.
Rocket-born launchers should work in salvos and allow people to do massive damage in one pass (possibly increasing the reload speed a bit to balance the fire rate a bit), regarding that ammo cost it is a bit more than any other traditional gun system in-game (cannons, rail guns etc) and should reflect their damage a bit more, the other weapons are more capable against ships (even seeker missiles since they're following relentlessly - unless the enemy ship has point defense or flares) which makes sense but we should have better variety in game regarding weapons: some of them have become useless at this moment (looking very dissappointed at mine launchers, torpedo launcher and other niche - broker unlockable or powerplay faction guns) and I would love to see the game support more types of gameplay, strategies and actually repaying your thinking and efforts, not just google what weapon is OP and copy-paste what everyone else does with their ships.
The rockets balancing factor is already present - very limited ammo (even engineered other weapons wil get more ammo if you focus on High Capacity engineering) which forces players to carefully aim their shots even more compared to plasma launcher, rail gun, etc. and should stay the same - but the rockets you've got once equipped should be worth their value since you can go with lasers or multi-cannons and do more damage in the same engagement time since they're easier to aim and allows for constant fire if you can keep your weapons on target and you still remain with plenty of ammo to go after additional targets.
I would love to see some major re-work on weapon systems in this game since most of them are hard to use and their damage potential is laughable compared to their counterparts - especially when they get engineered (like multicannons, plasma launchers and laser weapons), and the worst of them is torpedo pylons: they're slow, easy to counter and even their damage is not worth it since shields can eat them up and you get no reload on the launchers (I see no reason why: the ship is big enough to have stowage space for additional torpedoes and the year 3300 should allow for a reloading mechanism on torpedoes, even WW2 ships could reload their launchers with torpedoes - so they should get at least 12 shots as back-up since you get 1 for small, 2 for medium and 4 shots for large hardpoint and even 4 torpedoes may not kill a ship if it's properly engineered, plus their ammo replenishment is quite costly - it's like shooting sidewinders from your pylons since 1 torpedo is worth 15.000 credits and 1 sidewinder is 32.000 credits ).
Also - the flares are the most useless countermeasure out there due to their laughable ammo count. I don't see why flare launchers couldn't have more ammo and make them as an alternative for Point Defense utility and become a better defense for missile (the seeker-capable ones) spammers.
As for dumb fire rocket launchers (since this is the core topic on this thread) - I like to use them on surface targets and I believe this is where this weapon system should shine the most and the devs should improve their damage potential, at least on this role. If anything, I would love to see more surface type of combat missions not just on-foot pew-pew ones, like SRV hunting, skimmers, enemy "dropships" launching troops on a post etc and you get the option to make attack ships or dropships capable of hunting down other stuff, not just other space ships. And, I repeat: the rocket launchers are and should be ideal for this kind of role!