Reasons for remove copper-processing tech:

1. Realism. Humans have known about copper for thousands of years. We don't have iron-processing in game after all, but iron was developed later!
2. Oftopic. This is mod about aluminum, not about copper.
3. (most important). Сompatibility issues. If some mod unlocks wires early, then the recipe will be changed and we will get copper wires made from aluminum!

Reasons for add aluminum-processing tech:

It's a modern technology. Aluminum was developed about 150 years ago.
Tech that unlock aluminum plates and wires would be appropriate here, I guess.

Hi again, and thanks for your thoughts!

In terms of realism, I've answered a similar question in this recent thread. But the general idea is that I view vanilla factorio less as a re-creation of tech history, and more as recovering recently-understood technologies by an individual from a very technologically advanced society. This is a bit of a different approach from, say, Industrial Revolution 2, which does indeed take that historical perspective.

More specifically, one core piece of this mod is to establish one general trait of aluminum as being a general-purpose "electrical" metal (among other traits), whereas copper largely remains the general-purpose "electronic" metal (among other traits). In order to establish that feeling a little more clearly, I chose to put copper as an early unlock, so it feels a little more valuable, and aluminum feels a little more mundane. This also reflects our modern-day world.

Indeed, as you point out, the primary reason to remove the tech would be compatibility. I believe I've solved the general issues you raised around recipes/ingredients appearing earlier to prevent weirdness or deadlocks. If any new compatibility issues arise, I hope to solve those in implementation to keep the core flow of the mod as is.

I'll try to add something to this mod's FAQ to address the realism/historicity question.

And one last note. If you are interested, I'm currently working on a sort of cross-mod "lite" setting that would get rid of most of the modifications the mods make, and supply only the core resources, intermediates, entities, and relevant recipes, etc.

More specifically, one core piece of this mod is to establish one general trait of aluminum as being a general-purpose "electrical" metal (among other traits), whereas copper largely remains the general-purpose "electronic" metal (among other traits). In order to establish that feeling a little more clearly, I chose to put copper as an early unlock, so it feels a little more valuable, and aluminum feels a little more mundane. This also reflects our modern-day world.

Ok, now I see.
In this case I'll probably just replace copper cable with aluminum one in the starting tech of my Research Desk fork if your mod is loaded.