Why bother putting all these engineers out there when the selection of modules that are available out there aren't even worth engineering?
Engineered B-rated kit is still pretty powerful. Sure, the ability to get masses of surplus cash means that most players consider A-rated equipment the only sort worth fitting as neither cost nor availability is normally an important factor, but that doesn't mean B/C-rated kit is bad if you can't get the A-rated bits.
For example, on an Anaconda, the difference between A-rated and B-rated thrusters is 8m/s top speed and 4% extra agility. Applying DD5 adds another 80 m/s and 35% extra agility (to either thruster type, assuming a mid-weight fit otherwise). Does it really matter at that point that you only have B-rated thrusters? 99.99% of the time, no.
On a Vulture, the recharge on a 5A distributor is 4.3/2.5, whereas a 5C only manages 3.6/2.1 - but a 5C with charge enhanced G5+experimental is 5.4/3.2. Not as good as the 6.5/3.8 you'd get from the same mod on a 5A ... but the engineers - once upgraded - will be considerably more valuable to the region than having A-rated outfitting would be.
I have a G4-engineered B/C-rated Krait that I built entirely out here. It's not quite as powerful as my G5/A-rated Python, but the difference is largely irrelevant in practice.
With Frontier's obsession with community grinds, er I mean goals... You would have thought by now there would be goals in Colonia to improve the selection of outfitting options.
There have been at least three community goals in the last two years leading either directly or indirectly to significant increases in local outfitting, plus a couple of "free" upgrades reflecting general development of the region. The original baseline was "a badly-damaged tourist station with a population of 75", though, so going from that to "Shinrarta but without the permit requirement" would be a little unrealistic.
The total population between all systems in the region is just over 9 million and all the infrastructure has had to be built up from nothing - even with the strong high-tech focus of the economy that's not going to get a full selection of A-rated equipment in a hurry ... but it comes pretty close with everything except some of the larger internals fully available somewhere.
There'll be further upgrades in future, but what there is can already equip a ship for any purpose except serious PvP, so it's not as if it's a top priority.
Colonia seems like a pointless waste of time.
It is not, shall we say, designed for min-maxers - thankfully, since the salt from "why do we have to travel 22,000 LY to get the best X" would be unbearable.
(Similarly, given your quote above on CGs, a region that you have to work on to improve may not be for you?)