I think both points have validity but I've understood Nike's strategy to be much like what d e beatup described, all hinging back to when Nike and Venator/FL fell out years ago. It was understood then that Nike didn't want to fall into that situation again (where they relied on retailers) and they shifted their focus on how they treated their retail doors across the US. That's why factory stores stock better products now, have a different, more polished look, etc.
As far as the liquidation strategies go, I can't really speak on that. But I wouldn't find it hard to believe that Nike still has a lot of certain models still sitting back.