I think there are many issues being discussed here:
1) missiles are too strong at extremely large ship sizes (5m, 10m, 20m +) - Mc2
2) missiles are too strong at small ship scales in PvE - Atarlost
3) missile kiting is too powerful - SpaceCat
4) missiles should not be viable without supporting weapons to kill PD - SpaceCat
5) ROD should not be necessary to balance missiles - SpaceCat
6) PD is way too cheap for how good it is against missiles - Dalas120
#1 I agree with. Despite being prohibitively expensive, missiles scale better than any other weapon because they don't require forward surface area. To help balance this, I think that each individual PD block needs to be significantly more effective vs missiles, with a higher kill chance, fire rate, or similar. This makes PD very surface-area efficient, which helps to combat the surface-area efficiency of missiles.
#2 I don't have any experience with because I don't play much bounty. That being said, a $200k ship can have, at the absolute max, 4 missile launchers+factories+crew. 3 shields are enough to completely nullify those launchers (which you'd probably have already). Missiles can miss and wrap around, but that makes them extremely vulnerable to any PD at all. I personally don't think missiles in bounty should be an issue, but I realize that my experience is limited.
#3 I disagree with. I haven't been having any trouble with missile kiters - I just build a big PD wall and they can do literally 0 damage. Or I build a fast cannon wall and chase them down while my shields block most of the damage. Or I just set the timer to 5 minutes and sit in the center with a big immobile armored barge. That being said, I don't think missile kiters are very fun for either the kiter or the antikiter.
#4 I have mixed feelings on. No other weapon is completely worthless when spammed - even electrobolts can deal respectable dps if you have enough of them. Even if we were trying to force ships to kill PD before using missiles, it would take huge changes. Right now PD can be spread between all your other weapons, meaning that to kill PD you need to kill the entire ship anyways - so what's the point of even bringing missiles? Even if people do cluster their PD and make them easy to kill, missiles don't deal a lot of damage anyways.
#5 I agree with, but I don't think there's an easy solution. I would personally love a king of the hill game mode, but that's still similar to a ROD. If we just buff PD, missiles become useless altogether, not just on kiters. IMO the only way to do this is either 1) make missiles extremely heavy (thus no kiting) or 2) add a new, longer-range weapon that's heavy. As long as the longest-range weapon is also lightweight, it's not going to be balanceable without a ROD or objective.
#6 is my opinion. Right now $10k PD still beats $50k missiles. That's way too extreme. I agree that PD is very specialized, but this is just too extreme (at least at ship sizes where cost matters). Maybe PD could get an additional use in addition to a cost increase. Or make sensors part of a PD system to "stealthily" boost PD cost, and give sensors an additional use. Or keep PD cheap, but force it to cluster so it's extremely easy for non-missile weapons to destroy. But I firmly believe that 1-5 cost effectiveness is not healthy for the game, especially when PD has only 1 use.