If this feature is enabled it will allow us to enrich the forms. As an example we could populate a dropdown list automatically by pulling this data using an API call rather than manually populating the list for each form, will also enable us to embed maps within the forms, etc. This feature can bring a lot more customization within forms
Meanwhile, there is a bit of a workaround available - since 5.5.0 there is a script.js file that can be hosted in Agent Desktop branding folder ($root/conf/branding//ad-theme/js/script.js) that will be loaded into Agent Desktop window.