But if 99% of people use them for storing their random junk then wouldn't it make sense to design them for that purpose?
how would you propose they changed the design in order to make them more fit for that purpose?
surely by the fact that so many people already do happen to use them (rather than say the attic or spare room) for storing junk would imply that they are already well suited to that purpose anyway - i.e. no need for insulation, big door at the front so easy access & situated on the ground floor.

? Tell that to my dad and his corolla
.