Philosophy goes through self-conscious, periodic bouts of historical forgetting.* These are moments when philosophical revolutionaries castigate the reading of books and the scholastic jargon to be found in there, and invite us to think for ourselves and start anew with a new method or new techniques, or new ways of formulating questions (and so on). When successful, what follows tends to be beautiful, audacious conceptual and even material world-building (in which sometimes old material is quietly recycled or reinterpreted). Hobbes, Descartes, Bentham, Frege, and Carnap are some paradigmatic exemplars of the phenomenon (that has something in common with, of course, religious reformations and scientific revolutions). There is a clear utility in not looking back.
What’s unusual about utilitarianism is not that it’s a nearly continuous intellectual tradition that is more than two centuries rich. Even if we start the clock with the pre-Socratics that’s not yet a very old tradition by the standards of the field. But rather that it has become so cavalier about curating and reflecting on its own tradition. In one sense that’s totally understandable from within the tradition: the present just is the baseline from which we act or design institutions or govern society (etc.). Spending time on the past just is opportunity costs foregone or, worse, a sunk-cost fallacy. Worrying about path dependencies and endowment effects prevents one from the decisive path forward.