Older pyramids in better shape than the newer ones?

[stevenshaw]

[FONT=&quot]The title kinda speaks for itself, just asked myself while googling it. As you can see in wikipedia article, the older pyramids, like the Red and the Giza ones (4th dynasty), are in waaaaay better shape when compared to the "newer" (12th dynasty for example) ones.[/FONT]
[FONT=&quot]Why is this?[/FONT]
[FONT=&quot]tl;dr: Older pyramids look better than the most recent ones. why?[/FONT]