Where Settlers is concerned, there has come a point in literally every game where I wonder aloud why I have cities and seaports but no real military to defend them from my unfairly expansionist, resource-hogging neighbors. Because nothing says "you know, it would be mutually beneficial if you offered to sell me some bricks at a reasonable price" like an infantry division in snazzy uniforms massing just on my side of the border.
So you're right that there's more conflict and randomness in Settlers than in a typical Euro, but not enough conflict.
Maybe it should have been called the Hippies of Catan ''Peaceful opposition maaannn! If you don't trade some wheat with me, I'm gonna build a road to stop you!''.... Which makes me think, we don't know what's really on those roads the opponents won't dare to take...... But yeah, I tried Settlers a couple times, but it's not on my personal replay list. I can see the appeal and why it's considered a classic, it's just not my kind of game. Same goes for Agricola or Caverna....