Master Slides in Keynote- broken concept?

Hi,

I have looked through the forums for an answer on this and although I am seeing some people who have worked around none who have actually accomplished this:

I want to make a change to all my slides. I would like to add a footer. Very simple concept, but seemingly impossible.

Although there is a "master slide" function, apparently Apple decided that there is no need to have a _single_ master slide that can apply to all the slides in a given presentation. Yes you can do that if you make every slide based after ONE of the layouts but then you'd have a very boring presentation that doesn't leverage the other layouts in the theme for mixing multimedia and other things into the presentation. Powerpoint has had this for years but I just don't see it in Keynote.

If you want to provide a "master" function it really should be a master. Instead, every time I decide to use a different layout from the theme, it carries the burden of having to recreate the footers and headers that I want to be consistent throughout the slides. Note that it seems that those terms (footer and header) have been co-opted into discussions about tables instead of the widely accepted concept of including something on every page.