The default location of the Media Cache is on my C:\ drive. I do not like the C:\ drive to be used for temporary files. The constant creation and deletion of temporary files on the C:\ drive greatly increases the chances for corruption of that drive. Instead, I partition a separate drive to use for temporary things like caches and my Temp folder.

Alternatively, some people might want to put the cache on a fast SSD drive while leaving their C:\ drive as a standard spinning disk.