Land is still the primary source of economic value. And I don't think land was getting fairly allocated between all the peasants during the late 1300s.
It wasn't but you had the opposite of the effect that you have now. Right now the top 1% are getting a lot of the additional wealth that's being created, while the bottom 99% stay mostly the same, or improve at slower speeds. So yes, this means that we are headed towards a more inequal world, even though the situation improves for everyone.
Turn that now around, and kill a lot of people from the bottom 90% while letting the top 10% survive at higher rates. Suddenly, the world looks way more fair, even though the people at the bottom still have nothing.