We have actually thought about resources behind-the-scenes already.
One thing we don't want to do is making them essential. Some people simply don't want to bother. But some do.
So here is our solution, so far. Keep in mind that these are just some thoughts. Nothing is decided, yet:
There will be a small number of resources, basically food, wood, stone and/or metal and finished goods. As you can quickly see, different region types would have different strengths. Rurals would mostly produce food, woodlands mostly wood, mountains mostly stone/metal and cities mostly goods. Townslands, badlands and strongholds would be somewhere inbetween with a mix.
The resources would serve various purposes. Basically, food is necessary to feed your peasants, wood and stone are for constructions, metal is for troops and goods are for keeping your people happy.
However, here is our solution for the "I don't wanna bother" player: We introduce a virtual global "market" with fixed prices. When you don't have enough stone, say, for the next fortification level, your servants will automatically buy it on the global market. So if you don't want to bother, you can simply ignore it. If you do bother, you may be able to buy it cheaper from a trader, though.
Same on the producing end: If you don't want to bother with all the wood your woodland region produces, you can auto-sell it on the market and simply turn it into gold income. Sure, you could bother and maybe find a trader who pays more for it. But you don't have to.
That's just some rough ideas, so don't take it for gospel.