Metallurgy and blacksmithing overhaul
In my opinion, metallurgy and blacksmithing are too simplified in the game. You can't just melt iron ore into ingots in the oven. In general, it is impossible to melt any other ore into ingots without using molds.
I really like how the metallurgy is implemented in the TerraFirmaCraft mod for Minecraft and I want somewhat similar in ME. Soft metals like copper, tin, bronze can be melted in a simple furnace and then casted into molds. But for melting iron and steel, much higher temperatures and more complex technical processes are needed. For example, here is a link to the WiKi on TerraFirmaCraft metallurgy: https://1710-wiki.terrafirmacraft.com/Metalworking_Guide
Each metal has a temperature at which it can be processed on the anvil, and a melting point. Soft metal tool heads can be cast into molds, and refractory metal tool heads can be forged only on the anvil.
I will quote from the GitHub page, which describes very well what I expect from ME:
The goal of TFC is to make things more believable, and to give the player a sense of accomplishment. Mastering skills, and searching far and wide to gather materials before you can build amazing castles, homes, fortresses, towns, cities, etc.