For the last time, its not that people didn't know it would be wrong and a politically, morally etc heinous act. Its just that you do this kind of thing all the time, and it never counts anywhere else,
Take the tomb in the Emerald Graves. Taven invites you to join them, you find them dead, avenge them, find history etc etc etc. Great, well done you.
And then you swipe everything else in the tomb for yourself, pillaging resting places, looting treasures etc. And do the Dalish give a damn any of that? Do they hell. Neither do they care if they roam the Dales, massacring Halla by the dozens - in sighr of their camp!
Arguing that people should have known assumes Bioware is consistent about monitoring and punishing/rewarding such things. And they aren't. Common sense tells you most of it, but if you apply that to every circumstance, you will frequently miss content, lock out quests and miss good loot when you didn't have to. Most of the time, Bioware just let it slide and don't punish you, and like I said with the Priority Missions in ME, they will actively punish you sometimes for taking the common sense approach (i.e assuming that when you're told a mission is urgent and must be done right away), you can actually leave it indefintely and in fact *should* do that to get the most content for no punishment. Yet you couldn't have known that beforehand.
In ME1, you get a distress call from a team on Virmire. 'Check it out - they could be in trouble!' say the Council. But going there means losing a crew member and possibly another (much more likely if you go there early). So most people leave it til last, months after the team sent the call, and if it was being true to life, they would have been long dead when you finally arrive.