I don't know of any program that does a backup as just a copy of the files. They all have their own file format. Windows uses .zip files to compress the data.
I haven't had any problems with 7's backup, knock on wood. I've also used Acronis and Paragon products and they have both done the job. Haven't used Macrium, but a lot of people here recommend it.
The purpose of a system image is that if your OS gets tanked, you can reinstall the image and all the programs etc. will be restored also. No need to install the OS and then install and set up everything else. Whenever I make a clean install and get things set up as I want with programs installed etc, I make an image. I can now go back to that setup with a few clicks. Similar to the restore to factory settings option on a prebuilt machine. If I make major changes, and everything is working fine, I make another image.