I work in a industrial supply chain. Experience has taught me that customers will buy as cheap as possible that just works. I can offer a uber powerful 15 amp power drill with laser pinpointing,but at the end of the day they will buy a 2 amp B&D, after all , its only going to perforate into drywall.
That said, manufacturing costs for N series phones were very high, even higher than first gen Iphones. I can only guess that when Nokia tried to market them through major carriers, the carriers asked if these phones could be subsidized through a contract and make a profit on that. Looking only at the bill of materials costs, that would not be even thinkable. Therefore, carriers declined N series phones and went to cheaper E series phones.