Aha enables users to create custom fields for their Ideas and to arrange them via custom layouts. The Idea Details View is the only full screen view of the Idea however, the Idea Details View you cannot adjust the location of the fields you create to be in the center, they are still all show on a small section of the side.
The benefit for me to have a customized layout of the full view of the Idea (or Feature, etc.) is to be able to discuss Ideas during meetings by sharing my screen.