You can define a background for an application but it makes an application fancier if you also could define a background per screen (main subject). For instance, to make a difference per module. Of course, all the data fields should have their own “any preferred color” background.
From a user(s) perspective: A user would see the company identity as background picture. An important configuration setting for this background picture could be the transparency as in most cases the data fields are more important. The admin of the application would be able to set the transparency to I.g. 40% in order for the end-user to keep focus on the data fields.
