Honestly, this is more about making changes, based on how they interact with other ships in the game. Which is the thing that is often (and some might argue conveniently) ignored during a spate of demands for changes. The gulf between FDL potential damage, and type-7 shields, illustrates that whilst you can definitely make a ship a pretty nice PVP machine (honestly the ferdi is just beautiful to drive now; it was always good, now it's exceptional) doing so without considering other ships is actually borderline irresponsible.
We have core trading ships that are basically compromised to such a degree as to be redundant for all but certain PVE actions; and to me that's a waste. We have a lot of ships and I'd like to see there be more reasons to diversify. Yes, there will always be the 'optimal' PVP ship and build; but it would be great to see there being 3-4 equally viable ships; based on differing reasons. Basically it's ferdi for silent running and fas for hull.
That's okay though; commanders will fixate on a particular attribute and suddenly another ship will become the new blue; it's how it seems to work out at present.
The thing is that, in a game that contains assets, or ships/fighters (whatever), with fixed weapons and capabilities, they are already more often than not balanced against each other. The devs have full control over configuration of the ships, and all the player can do is to work out viable tactics or gameplay to get an advantage. "Meta"-ing still exists, but players will seek to exploit tactics or maybe even bugs in the game.
Once you have customization, you simply introduce more variables into the game. Along with tactics and exploits, you also now get potentially overpowered builds.
For a game like ED, that's unavoidable. After all, outfitting your ship has always been a core part of the game since the original. So FD has to carefully consider what kind of modules or weapons they put in the game.
IMO, stuff like HRPs and SCBs are always a mistake. In a pure combat game, these things will be fine. After all, the main objective of the game would be to kill each other. But then again the lack of consequences for loading up on HRPs can be somewhat baffling from a balancing perspective... even if this was a pure PVP combat game. Why?
You get all of the additional armor, and you lose cargo space which is irrelevant for combat... but then again, you also lack the balance of the traditional three main stats of combat ships:
Firepower vs Armor/Durability vs Speed/agility.
With HRPs, your firepower isn't affected, neither is your speed or agility. But your armor gets a huge boost. So everybody does the same thing. Plus you get the option to get a stealth ship, simply because you have armor to mitigate a lack of shield.
It's a win-win. Absolutely no drawbacks. There's no min-maxing here. At all.
Where's the glass cannon? Where's the stealth ship that has paper armor, or maybe moves like a pregnant pig?
In ED, you get a Ninja wearing bullet proof armor, and wielding a silenced minigun.
So now, Elite isn't a pure combat game. And once you unleash unbalanced HRPs and SCBs in to the mix, you are more than likely to make all other roles victims of these kinda builds.
But if you remove HRPs or SCBs, or maybe just disallow stacking, you would reduce the huge difference in stats these ships have. They would still be stronger than multi-purpose or cargo outfitted ships, but not glaringly so like present.