Hi egodestruct,
No … there is nothing objectively wrong at all with a 6" double sided mattress (probably with quilting on both sides) on a box spring. It’s just a difference in design from a one sided mattress that uses more progressive layering from the bottom to the top and is on a firm foundation instead. The firmness / softness of this type of sleeping system can be changed with the ILD of the latex, the type and pattern of any quilting, and the design of the box spring.
As you mentioned a double sided mattress will be more durable than a single sided mattress (assuming you flip and rotate it) even with a material as durable as latex. You can read about some of the pros and cons of single sided vs a double sided mattress in posts #2 and #3 here and the posts it links to.
Phoenix