It is not about providing more information, rather visualizing it in a different way. At the end of the day you could also avoid making Gantt chart to plan your project, and just have a column with all dates and predecessors etc…but in the same way as a Gantt provides better visualization of the timing and links, the other type of scheme helps visualizing the work packages differently. Ganttproject is just probably not the right tool for this, nevermind.