Still, even with the Ota fares, the price difference in the above example is about 100 euro. And that is assuming a very cheap paid fare.
However awards can be used in place of a very expensive summer fare. Sure you can find cheapish fares, but you may have to fly at an inconvenient time. It all depends on the person, destination and schedule. For some miles will work out better.. And for some buying a ticket would. Though I think that for most the award ticket will be advantageous.. Or at least offer a substantial discount over the paid fare.
Also keep in mind that not everyone is flying between major airports. Some smaller islands just charge a few euro taxes. Athens has some of the highest taxes in Europe.. But not everyone will be flying to/from athens either.