“I did begin a story placed about 100 years after the Downfall of Mordor, but it proved both sinister and depressing. Since we are dealing with men it is inevitable that we should be concerned with the most regrettable feature of their nature: their quick satiety with good. So that the people of Gondor in times of peace, justice, and prosperity, would be become discontented and restless — while the dynasts descended from Aragorn would become just kings and governors — like Denethor or worse… Not worth doing.” (J.R.R. Tolkien, Letters, #256, to Colin Bailey)
Tolkien was a great man. To realise the worth of a story even before it was written and then abort the project speaks volumes to me. He was a story-teller and not a mercenary.