Do the materials in SimCity 5 serve any other purpose besides income and great works?
My point is whether it is necessary or not, to keep producing facilities in your city after you have completed your Great Work?
It sure gives you the extra cash, and gives your Sims a place to work. But do they serve any other purpose to the city?
The alternative is to have more RCI in your city.
Benefits for specializing in a materials based city:
1) Jobs for your citizens
2) Income stream for you
3) Materials for completing a Great Work
4) Supplying another city in the region with materials for their needs
5) Materials for Oil/Coal Power plants
6) Giving your city an "identity" or a special look.
Drawbacks of a materials based specialization:
1) Pollution, which leads to sick Sims and an ugly city
2) The strong job requirement will cause you to require zero Industrial Zoning.
3) If you are only building and exporting Oil/Coal/Ore Mines, your city could become rather dependent on those funds, so when the natural resource runs out, you must diversify to financially maintain the city.
If by materials you mean the products from city specialization, for the most part no.
Of course coal/gas is used for power plants.
