Do you understand even the most base concept of torsional rigidity? Do you understand the slightest idea of how solid structure makes for more of it?

A hatch has a gaping maw in its ass end which loosens the rigidity of the vehicle in the rear end moreso than the smaller openings in the sedan and coupe.

Sorry man but you have no idea and this is the only way to explain it simply. The other way is to take you out in two completely stock Civics of each model and run you through the corners and let you feel the difference.