Years before World of Warcraft I played a game called Ultima Online. Spent way too many hours on that game. Probably the reason why I don't play them any more. What got me hooked on the game was the crafting system. It was a blast. Go mine up the ore, find a forge, smelt the ore, find an anvil and forge a sword.
This is an area in RPGs I rarely explore myself. I've played a blacksmith in a campaign. My job was to steal secrets from a rebellious baron. So fighting was not primary, blacksmithing was the focus. It was a unique campaign.
Imagine running a campaign where the player or players are craftsmen and their job to to create items to sell. Dealing with getting raw materials and developing a market for their goods. I think it would work well with a one-on-one campaign. I think this type of campaign would work well with a points based system.
Even if you have a system to make the crafting challenging you still need to make it interesting. Interesting enough to last over a length of time. I think it could happen. Granted, there would be a lot of fetching quests. The player would need to go get this or that to make their item more powerful. Conflicts with business rivals, possibly a local gang pressing for protection money and of course you can always throw in some political mumbo jumbo.
In the campaign I'm building crafting will be apart of the game. The players can of course choose to indulge in it as much or as little as they choose. But I think it adds a depth to the world and to some of the adventures. Those who've read my adventures there is always a little thing in there that can tweak the effect of a spell of potion. Find a large spider web and cut the center out to see your web spell double in area. Those little red berries when added to a healing potion increase its effectiveness. These of course can be added without going into detail, just interesting bits the players can use, but when used with a crafting system then I think it become more interesting.