Personally, I play in peaceful until I get to a point where I have armour which means I have less than a 1% chance to get murderized. I don't find mobs to be an enjoyable part of the game.
However, even though I don't fight mobs, I generally have keepInv. on, just because I am my own worst enemy for navigating (I don't take torches when I'm in caves, as I don't need to stop mobs spawning), so I go wondering around darkish caves (I can't play MC without brightness on max) and get lost very quickly, so dying in the caves is a pain, even with a minimap mod that marks your deathpoint
However, even though I don't fight mobs, I generally have keepInv. on, just because I am my own worst enemy for navigating (I don't take torches when I'm in caves, as I don't need to stop mobs spawning), so I go wondering around darkish caves (I can't play MC without brightness on max) and get lost very quickly, so dying in the caves is a pain, even with a minimap mod that marks your deathpoint