Theory vs. Reality; The Davidic Kingdom from Construction to Destruction

Why would the mizmorim of Asaf, the sons of Korach and David be presented in separate collections in Books II and III of Tehillim? Wouldn’t it make more sense for psalms by the same author be presented together in one place and not divided between books? Books II and III in Tehillim, comprised of collections of mizmorim attributed to several different authors, are considered to be one unit. Contextual interpretation shows that these books move along three axes; 1) the destruction of the Temple and kingdom of Israel which lead to Exile; 2) in contrast, David is the epitome of the ideal kingdom under God and longing for the Temple and; 3) using this model to breathe life into the vision of the redemption of Israel which includes the rebuilding of the Temple in Zion, ultimately to include all the nations of the world. Unfortunately, this vision does not come to fruition due to the realities of the Exile. The structure changes for the better in Book IV.