In winter there is little holiday travel to Greece. Most people travel for business or family. Both of those make a lot of sense in randstad, as most of Greek diaspora is in that area I believe. Considering that the second daily AMS flight was likely lost due to slot issues (And not nesesarilily because they wanted to reduce capacity...) it also makes sense to operate a flight to the same area around Amsterdam. For most of the country RTM would be easier to reach than EIN... by public transport at least.