Another person assuming everyone playing this game has the resources to buy A-rated modules and G5 engineer them all. The price leap from B to A is often HUGE, data you might want to add to your charts.
The price difference isn't that large really though. Large in terms of percentage, perhaps, but the overall price is still pretty irrelevant as income rates have soared in recent years; a 3x increase from a very small number is still a very small number, albeit a bit less small. Even for an Anaconda, the difference between A and B rated thrusters (34 million credits) is basically just 10-30 minutes of gameplay away with current earnings. This isn't 2016 where 5 million credits an hour is good earnings, we are now in a time period where 50 million/hour is considered to be hardly worth doing.
We can't put the toothpaste back in the tube but we can certainly restrict the toothpaste supply back to 1st year levels.
That won't do anything about the toothpaste that is already saturating the local area, players that have abused credit earnings will still be left with effectively infinite money. No, what we need to do is to rebuild the tube around the house-sized blob of toothpaste and balance the game around toothpaste being available by the tonne rather than the previous pea-sized allocations per person.
To bring the analogy back to Elite - restricting income won't achieve anything as so many players already have effectively infinite money already in the bank at the moment. Reducing income might help new player experience, but someone with billions in the bank will still have the economy ruined for them as they have enough to buy anything they want for the next 5 years of updates; instead, costs need to be increased to match the new post-billions economy where earning 100+million an hour is considered to be normal in a high-end ship.
Considering how earnings seem to be at least 10x what they used to be, a basic increase of all costs by a factor of 10 would be a good start, although some individual ships and modules might need some extra tweaks on an individual basis to keep things in line. A cost difference of 34 million credits between 7A and 7B thrusters might be insignificant, but if that cost difference were to be increased to hundreds of millions then a lot of players would probably give A-rated modules a miss, either because they are expensive or because they don't like what that cost does to their maintenance/rebuy costs.