Hi everyone! I generally agree with the previous posts. In my personal experience, Mordor is getting the eco upgrades generally quicker than other factions. The cost is much cheaper, even taking into account Nazgul etc.
Let's calculate it: Most factions need around 600-1000 for the research building, and then 1200 per eco upgrade (around 4200-4600 in total).
Now, Mordor can pay 1300 for Nazgul, 1000 for Sauron, and 800+500 for CU unit (around 3500 in total). Mordor upgrades also "research" quicker due to infuence of Sauron cooldown time.
Besides the eco upgrades, after paying all that money most factions get the benefit of having a forge, whereas Mordor has a hero, elite units and other very useful hero that cannot die (as Smeargollum Said, it is the same as if Gondor would get their upgrades by buying Aragorn and Gondor cav or Rangers).
So the Mordor eco upgrades seem cheap for me, even free at their core. Making them have some cost and potential research time would be ok for me (not necessarly as high as other factions, could be a cheap-quick one). As Mordor is a faction with many other free features, I don't see them having eco problems either. If we want to keep that "free thematic motive" for Mordor (which I don't understand even from lore point, maybe besides the free orcs), then other changes should be done to achieve a similar effect (I can think of moving Influence of Sauron to level 4, but I am not sure I like it).
Now, Mordor has other problems that would remain the same, mainly their high contrast between nearly trash
earlygame, and their megastronk
lategame.
Butaybe it is better to make changes slowly, since a new patch might come soon with more changes.