Centralizing the training of our "public servants" makes the creation of a bureaucratic mandarinate--a French (not to mention Chinese) thing, which ought to be enough to sink it right there--all the more likely. Do we want a bureaucracy even more "out of touch" than it currently is? Do we want one group of professors to be that influential in the preparation of our political leaders and public servants? (My fear, of course, is that such an institution would be quickly captured by the Left. Their students would comprise our bureaucratic elite, and be even more resistant to initiatives from conservatives in the legislative and executive branches.)
But even leaving aside this political consideration, a centralized bureaucratic training institution would to some degree deprive our governmental institutions of the leaven of diversity that comes from the fact that those who comprise it are educated at a variety of different colleges and universities. It is more in keeping with the "federal" character of our country to have our leaders educated all over the place, not just at a handful of schools. They reflect regional, religious, and ethnic diversity. In their education, they encounter, not just like-minded "future public servants," but folks who plan to pursue all sorts of different careers and ways of life. This, in other words, is the federal, republican, and democratic way of educating leaders.
I am, of course, sensitive to one issue that the plans proponents raise: its harder for students to enter into "public service" if they have a high debt load. But that can be handled either through a program of debt forgiveness/repayment for those actually enter public service or by a well-funded (privately--Bill Gates, are you listening?--or publicly) program of scholarships. We dont need, and shouldnt have, a public service West Point, but we probably do need a public service ROTC.
Of course, its highly unlikely that such an institution would get off the ground. Surely Republicans would know better than to fund it. But Democrats? Hmmm.