What is the value of having a disk image versus files/folders backup?

Hello,

I have a full image backup defined as well as file/folder backups for important folders.

I've realized a couple of things:

1) I can restore individual files/folders from the image based backups (restore points).

2) file/folder backups do not support offsite.

What is the benefit of having one or the other.  It seems like to me that the image based backups are pretty large every night, is there such thing as incremental image based backups?