Some sort of defined credentials for ministry are probably necessary but there's not much about a seminary education in particular that provides anything truly essential that one couldn't get from a combination of some sort of humanities/social sciences background, personal piety and moral rectitude, and a Hard Lessons from Life degree from the School of Experience (which, as Flannery O'Connor tells us, is the easiest kind of degree to get and stays learned the longest). I'm speaking as someone who has a formal theological education myself. Universities didn't exist for half of Christian history, at least some of the Twelve Apostles were illiterate, and while times have changed enormously, they haven't changed THAT much in terms of what basic kinds of people do and don't make good religous leaders.
At least for Catholicism, the academic level of seminaries has been in the gutter for some time now too. The real important thing happening is the pastoral experience and formation.
Or not happening, in some cases. But point taken.
