Well I don't have any objection to changing it, but what would I change it too? The plus and minus make perfect sense to me. I click on the plus to get more content, click on the minus to get less, and if there are no children under the element to show/hide then there is no plus/minus.
The only other options I know are triangles and filled/empty circles. These have a huge disadvantage, however, in that they can be used as normal bullets as well. So people can't tell right off if they are a bullet or a collapse control. I tried to Google this and apparently the Apple Finder even does use them as both bullets and collapse controls. It will have a right pointing arrow even if clicking on it does nothing!
Maybe they fixed that idiocy by now, but it just goes to show that even the UI designers mixed up that triangles are not bullets and should never be used as bullets in a program that uses them to indicate more content is present and that clicking will do something. I imagine that would cause a lot of fruitless clicks.
Is there a good alternative I'm missing? Maybe it's impossible to find a symbol that's obvious to everyone and it should just be '(click to show more)' or something like that. I do really like not having that wordy about section and that complex settings section cluttering things up unless people actually want to see them.