Key engineering in my eyes:
Powerplants: there is far too much power available allowing power hungry weapons with top end engines, shields all at once. If power is reduced it means Guardian PP + distro is a great choice (since it is equivalent to G4 in power output plus extra from the combo)- if regular engineering only went to G1 (+ experimental) you'd have a nice choice to make. Starving power also means that hulltanks become a consideration again, because shields + boosters + Guardian modules would eat power. FSD and engines are fine because they are then brought to heel via powerplant output.
Weapons: if weapons are not super pumped G5 then it means tech broker kit instantly becomes fantastic. Shock cannons would be really nasty for example- and a viable choice, not a novelty unlock.
Shields: de powering shields makes 10K shield monsters impossible, and that you can't stuff Guardian shield boosters / SCBs either.
My one dread is that FD are simply afraid to tweak anything at all, and want to leave it as it is.
On PPs: You are basically right. But you can't simply retroactively reduce the power output of existing PPs. If you do, there'll be plenty of ships exploding for no good reason right after the patch. There will be players around who won't religiously follow patch notes, yet have engineered ships which take advantage of existing PP engineering.
Having ships explode after a patch will be seen as unfair and thus is not a good move. At the same time, you can't just decide that existing PPs remain the way they are, while new ones will be weaker. If that'd be done, I'd just before the patch stack up on fully engineered PPs and create yet another layer of "newer players can't ever get this". Which is not a good thing for any game.
On weapons I agree that it's a thin line. You sure don't want to overnerf them. But a +70% from base still is too massive, before even looking at the special effects. But indeed, if tech broker weapons would be too far ahead, that has to be taken a look at, too. In my eyes fully engineered weapons would still have to be the the better choice. But I think that they currently are too ar ahead.
On shields, I think we both agree: that's where the big cuts would have to happen.
And on FD not doing anything any more: I am actually convinced that they won't ever touch this again. They more than once tried to do just soft nerfs, parts of the community cried rivers of tears and FD backed down. (While those who actually were in the beta and tested the changes found that they were quite soft, nothing to worry about, merely a step in the right direction. ) As FD didn't have the guts to pull through with even so soft nerfs, they won't ever dare to go for real nerfs.
Why though? I'd reduce all that including the mods you mentioned, even if that means I have no 80LY conda any more.
I'd wager there are only a handful explorers out there in systems so far out of reach, and for the goal of nerfing this power creep I'd gladly give support a hectical day or two.
And for all others: well we have to cope with that, and build accordingly. No more instant armoured pp for everything.
Matter of taste and impact. I don't think that the 80ly Anaconda is any balancing problem. No matter how far my enemy can jump, it doesn't increase his damage output or how much of a beating his ship can take.
So why take something away from explorers, who don't really hurt anybody here, if it doesn't really affect anybody negatively? Any nerf results in negative feedback. That's the price you pay for it, so you better make sure that what you get for it is worth this price. I think that the game would benefit from nerfs on shields and weapons, but mostly shields. It would make things much more interesting again.
And that's why I think that FDS engineering should not be nerfed. There's little to be gained, while still having to pay the price of negative feedback. It's not worth it.
Rather than hit powerplants, why not simply increase power consumption of weapons?
That indeed would work. But you have to take a close look on what things you apply the changes to. The base weapons would probably have to stay the same, while the engineering on weapons and shield boosters could get way more energy intensive.
My reason behind that thought again is on the side of not combat oriented players. The long range explorer might still have his mining laser along. And he's not the one who needs nerfing, while he'd have to spend an inappropriate amount of time and effort to travel back and adjust his setup.
In contrast, the combat player usually docks at a station regularily. Adjusting the setup for him is more easy, so it's not that a big deal if combat ships have to be adjusted.