My understanding from talking to the pilot is that the Polar route is in fact more frequently used in the Asia-Europe direction than in the Europe-Asia one, I believe due to the winds (wind typically blows from West to East in the Northern hemisphere, so by doing the polar route to Asia/outbound, you end up getting headwind as opposed to the tailwind it would have been with other itineraries. By contrast, on the inbound/from Asia you gain tailwind instead of headwind.