Many people despised the end of Stephen King’s The Dark Tower series. I did not. I think they wished for some epic, climactic battle where all moral and plot questions are unequivocally answered. In my youth, I probably would’ve been more desirous of that too. Having the Tower defended by an insane king with nearly no followers, all of this occurring in a decaying, weirding world, seems now completely appropriate to me.
With the benefit of experience, life doesn’t proceed in a manner where you achieve all your goals in some decisive confrontation. Furthermore, the journey is all there is, really. In the books, the Tower (among other things) is a representation of birth and death, neither of which we by their very nature can recall. So reaching the Tower is a nullification of experience, of meaning, of purpose. Reaching the Tower means there is either no more left to do or that one must simply do it all over again — just as in the end of life and its beginning.
As a symbol the Tower is polysemic because not only is it the goal of different people for varying reasons, but because the goal of one person contains different meanings and imperatives at various stages. Nominally, the idea is to correct whatever’s wrong with the Tower that is causing the world to fracture and decline. However, the world’s splintering and the shirking of responsibilities and higher duties has (as the book implies) the reverse causality than the characters expect — you don’t fix the Tower and that rights the world, rather you right the world and the Tower takes care of itself.
The ending of the Dark Tower series delivered a more ambiguous moral message than many wished for, though through all of the books the morality is not Manichean at all. It’s not clear why they were expecting anything other, given the rest of the series. Nevertheless, there is a moral clarity of sorts, just not one they were seeking. It is this: that how you treat your paramours, your loves, your compatriots, your friends, your traveling companions, even your enemies is more important than your ambition and your objectives. Else, you have to keep doing it until you get it right.