Because that's what it says to do in the Medieval Warfare 101 textbook, under the heading "How to Sack a City/Castle." You either occupy it or do your best to destroy it to deny it to others. It doesn't matter that there were no defenders -- you round-up the populace, take everything of value that can be carried, then either murder everybody outright or march them off toork your fields, kitchens, etc.. Peasants, sadly, were treated as chattel, one step above outright slaves. It's pretty obvious to me Ramsey's men did the sacking, either after letting the Ironborn besides Theon go free (as Robb commanded), or, more likely, double-crossing them after they opened the gates to surrender. I guess the Ironborn could have done it as a departing F U, but then where are Ramsey's 500 men who were previously besieging them? I think Ramsey did it with the intent that it be blamed on the Ironborn. I gave this episode a 9, mostly because I have largely separated book and show in my mind into 2 separate entities; not totally, mind you -- they still have to bring the story to the same place, but if they go a slightly different route to get there, I'm fine with that. The fact is that, as much as we book lovers b!tch about every little change, that criticism simply has no bearing on the average TV viewer. Media buzz, ratings, and critical assessments are all still very positive.