Re: define-derived-mode

[Richard Stallman]

    If one would make it construct defcustoms, then maybe that should only
    happen if the :group keyword is given, so it would not get into the
    same default group problems as `define-{minor,generic}-mode'.

I don't follow the logic of this argument.  Whatever group is right
for the move variable, isn't that right for the hook variable too?

However, I am not sure we want defcustoms for *any* mode hooks.  How
often would a user want to customize one with defcustom?  It seems to
me that defcustoms for mode hooks are mostly useless clutter.

What argument is there that they are useful and worth their cost?