I'd agree, except sooner or later I want to kill those monsters for their XP. As soon as you start fighting, everything in an area comes down on your head and getting away from them can be difficult. Very difficult. Lethally difficult for "true" rogues with a lower damage output. Hence why many of the recommendations for Sneakiness involve upping first strike damage, giving the rogue more time to slip away into the shadows before surrounding mobs show up on the scene, or making traps more useful and allowing the rogue to deal damage without actually being in the same room as the stuff he's pissing off.
There is, however, the problem where monsters that aren't labeled as "peaceful" will follow and attack you despite their mouseover claiming they haven't detected you yet. They only get the detection exclamation mark and the "trying to kill you" status once you damage them, but they'll still hunt you down regardless. And the "peaceful" label is a crapshoot as well; I've been getting random flamers being considered peaceful, but others aren't.
