>  From the "GNU Emacs NEWS" on GNU Emacs 24.1:
>
>  > *** Custom options now start out hidden if at their default values.
>  > Use the arrow to the left of the option name to toggle visibility.
>
> Is there a way to revert to the old behaviour, e.g. to always
> show the values of  options, no matter whether they have been
> customized or not?
>
> I think I have tried every seemingly related option in the Custom
> customization group and relative subgroups.

Actually, I see that NEWS item, but I do not think I see that behavior, IIUC.
In emacs -Q, for instance, if I do `M-x customize-option auto-coding-alist', I
see the full standard (uncustomized) value immediately.  (I'm using MS Windows,
in case that makes a difference.)

At any rate, if some Customize behavior does not seem right to you, or if it
does not seem understandable or correctly documented, then consider filing a bug
report or an enhancement request.  You can do either of those things using `M-x
report-emacs-bug'.

Perhaps see also bugs #11655 and #12065, which likewise have to do with
hiding/showing information in Customize.

http://debbugs.gnu.org/cgi/bugreport.cgi?bug=11655
http://debbugs.gnu.org/cgi/bugreport.cgi?bug=12065