From a UI and an OS X perspective, customization buffers should 
    definitely go into proper dialogues with native widgets.

Most cases, perhaps nearly all, would be easily handled with those
native widgets.  But it might be hard to make this support everything
that Emacs customizations actually do.

Meanwhile, we could afford to maintain this for one set of widgets,
such as GTK.  But if the idea were to use the native widget set of
every system, you're talking about a tremendous amount of work.

    Successful OS X software pretty much always uses the native user 
    interface.

The purpose of Emacs is to enhance the GNU operating system of which
it is part, and thus to contribute to the liberation of computer users
from non-free software.

Mac OS is a non-free operating system.  Viewed amorally, as mere
technology, it may be useful; but it is fundamentally unethical.
Our goal is to replace it with free software, not to enhance it.
To produce "successful OS X software" is a distraction from the goal.