I think Andrew Thompson nails it. I know my own reluctance.
I have always suspected that our fears of being personally responsible for telling anyone ‘no’ has led to our willingness to hand over the ordination process to a bureaucratic system. Our present American conception of individual liberty has led us to never want to presume to tell anyone ‘no’ in any instance. That is particularly the case when it comes to discerning a calling from God, which each ‘called’ person believes is authentic. So by handing over ordination to a bureaucratic system, we can be relieved that we don’t have to ever say ‘no’ and hope the ‘problem candidates’ get weeded out in an impersonal way. This is, I believe, exactly an area in which we need to be countercultural. We have a responsibility to God & the church to say ‘no’ when ‘no’ needs to be said, and ultimately that is a much more pastoral attitude to have toward candidates anyway.