Frequently it would be helpful to be able to display forms within model-driven apps either as a grid/table or by using nested form elements. Having the option to align fields to a grid sometimes gives a more user-friendly look. Other times it would be helpful to nest a two-column section inside a column of another section. For example, if I want to show multiple subtasks within a parent task, being able to nest them inside other elements would make a far more intuitive UI, and could allow for business logic to mark the parent task complete when the subtasks are completed.

Perhaps capping it at one nested level would add functionality/UX to the forms without creating excess levels of complexity?