This isn't the problem as people already want their stuff to be G5 and the people advocating for G3 are just telling people to avoid the bad engineering system as much as possible. It's not bad advice but it doesn't solve the problem that FDev should solve, perhaps with some sort of engineering overhaul
This.
And it doesn't help that a lot of module effects are pretty significant on paper
for that module "90% improvement" and suchlike ... and it's only if you stick the hypothetical build into Coriolis or EDSY that it becomes clear that doesn't translate to significant whole-ship performance differences. But the costs are pretty much
entirely dependent on the grade of the blueprint rather than on how useful it is. It's as if 6A Prismatics and a 1A Fuel Scoop cost the same amount of credits because "they're both A-rated" [1]
Lightweight life support (a complete non-entity of a blueprint which makes virtually no difference even to the Beluga) at G5 costs almost 1000x more in materials than G1 Dirty Drives + G1 Increased Range FSD which have tens or hundreds of times the effect. It's not as if the shielded/reinforced blueprints are any better: sure, losing life support is annoying, but explorers have space to carry an AFMU to repair it, and everyone else can hang onto a few low-grade raws and synth if they start running out before they can reach a station, and the main way to lose life support in combat is canopy damage which it doesn't help with anyway.
It's easy enough to avoid the traps with experience either personal or borrowed (almost all blueprints above G3 if you're remotely constrained on material reserves, most of the ones below that too) but outfitting is definitely one of the areas where ED has massively increased
complexity compared with its predecessors in a way that leads to a balance of 90% of choices being terrible, 5% reasonable, and 5% taking advantage of the system in unintuitive ways. And it was a mess
before engineering.
(Odyssey outfitting and engineering, despite some of the frequent complaints, does do a lot better in almost all respects: almost all "modules" and upgrades have a decent use, costs do inflate a bit fast at the really high end but that's counteracted by easier reuse of good stuff when you get it, the engineering addons have varied costs which at least attempt to reflect their power)
[1] Not that the actual credit costs of modules are sensible either. It's just that everyone has too much money to care nowadays, and if you buy something which doesn't work out or you no longer need you can sell it back for 100% anyway.