I don't get it
Mega charging by the MB for storage is not like Tesco charging a flat price per kg of food whether it is horse burgers or single malt whisky. It is like a courier company charging by the kg to move stuff, or a storage company charging by the m^3 to store it.
Why on earth should Mega charge different amounts for storage of files depending on some "perceived value" of the data being stored. Their scarce resources are bandwidth and disk space, so that's what forms the basis of their pricing strategy.