You really don't see a difference in complexity between:
System A:
Find a resource, build an improvement, build units up to that cap.
System B:
Find a resource, build an improvement, specify an extraction rate (trading off resource income and stockpiling vs depletion risks), build units consuming resources - but worry about losing them, because the resources are gone forever.
An elegantly designed game is one that is as simple as possible.
I don't want to have to think about resource extraction rates every time I build a mine.
Its also of totally the wrong scale: if your system really only has a resource be consumed when a unit is built, then even a single mine is letting you build one new unit per turn, which in effect means the resource constraint isn't binding.
It also punishes you even more than normal for not using resources - in your system, it doesn't matter how many units of the type you have, and losing a unit loses you its resource allocation forever.
other than trading resources
You have resource trading in the existing simple system.
If you lack the resources will make you think twice about invading someone
You have this in the existing simple system.
A motivation for expanding into other lands
You have this in the existing simple system.
And in fact, less so in your system, since other peoples' resources will be partly depleted and so less useful.
Pointless micromanagement is not fun.
Nor is resource depletion. This was one of the most hated features of Civ3.
Something that continues to be taken out from the civ series with every release!
Really... did you even *play* the early versions of Civ? How is Civ2 less realistic than Civ1? How is Civ5 less realistic than Civ4?
In Civ4, one oil resource was enough to fuel an unlimited number of tanks and aircraft and ships.
Remind me how Civ5 is less realistic?
Wondering....Is this a side effect of the drug culture or the consolers trying to sabotage the computer gaming industry by dumbing it all down to the point where your imagination is no longer required?
Wha? Civ5 is not a console game.
The Civ5 resource system is more complex than for Civ4.
How does your system require more "imagination"? It just requires more micromanagement.