You can definitely make a game like this and still keep the fun factor. One example that springs to mind is penumbra: overture. The game is the best horror-atmospheric game I've ever played and I highly recommend it. You can fight the creatures that you come across, and even kill them, but it is dangerous and not necessary. This might not be the best example, but it's the one I thought of. I do think though if you really want to make combat not the point, it should be possible (although maybe challenging) to avoid it entirely. Keeping with my example, there are stealth sequences where you are trying to avoid these patrolling demonic hounds. If you screw up it isn't game over though, as you can survive a fight with them. The idea is that the fight is a risk not worth intentionally taking. This can be seen in roguelikes where the enemies are actually intelligent and you might have to decide if it's really worth fighting a particularly powerful monster. You could extend this idea to encompass all combat.
In my opinion, I find that combat gets boring if there is no visible gain for me as a player. I like to see the exp bar go up, or to see rare loot get dropped. So if there is a LOT of combat, I think it needs some kind of reward (or it just needs to be really entertaining, but then that would make the game more about combat!) I don't know how you would have everything like a roguelike but still not have combat as the point. If I get stats and items, how are they not important to gameplay, but still important to combat (which apparently exists in some sense because there is a reason I am increasing my stats)? I guess another option would be to make the actual combat stats very minimal in comparison to other stats (for example horseback riding in your merchant example, to enable faster travel)