Would that really be a restriction? At that point units usually don't take that long to build, and if you can just ignore resources, you lose a big part of the game. It would be even worse with resources that are the result of a complex chain (especially in the later eras, but even e.g. Iron Wares comes to mind). Right now it is a bit of an achievement to reach it, and since the resource is often really powerful, it is also a strong reward. But if players can just ignore them (and resource producing buildings often have strong mali), it would be like taking resources completely out of the game. I really don't think that would be a good idea.Instead those units should be built faster if you have a certain resource.
The resource system also is one of the really strong aspects of this mod for builder-type players, and it would be really sad if they were left off with - almost - less than vanilla, perhaps even less than CivV.
