The DC of pickpocketing merchants affects me, because it affects how I play my game. And it affects how "real" the world feels to me. If stealing literally everything from a merchant is this easy, how does any merchant ever stay in business?
Thats interesting to me. So instead of playing your character as someone who would or wouldn't steal from a merchant your gameplay would change depending on how hard it is? And I leave my car unlocked depending on the location I am parking it and my perception of its safety there. So in the druid grove, I would expect the merchants to not be too concerned (unless the stereotypes of those filthy tieflings are true). Now the ones in the goblin camp...LoL.