To get back to answering Peter's original question from which we have strayed somewhat into reverse chucking methods, in a similar discussion on another forum, Mark Baker (Editor of Woodturning magazine) said:-
"I have always advocated keeping an open mind on how one finishes the bottom and I do not finish off each piece in the same way. Instead I look at what will work well with a given piece."
I think this reflects what I have been trying to say, somewhat less eloquently throughout this thread.
I do not condone poor workmanship or laziness but whether or not the spigot or recess that formed the chucking point becomes part of the finished piece depends upon whether it is relevant to the design.