The going cash price likely factors into the award pricing because they can still sell those nonstop seats for more money and therefore don't want to give them up for minimal points. Jacking up the points to some crazy amount that defies rational spending is a way for them to clear those miles off the books, should someone take the bait, but it's probably more of a discouragement to not redeem and give them $$$.
So that makes sense when comparing AUS-JFK vs AUS-DFW-JFK. But it doesn't make sense when comparing XXX-JFK-LHR vs JFK-LHR. If the JFK-LHR segment is so valuable, why give it up so cheaply if you start at XXX?