For oatmeal, yes. For mattresses, usually not.
This is true for most foam and all innerspring mattresses, and there is a personal connection to the phenomenon. I am sure that I did not invent “perceived value”, but back in the ‘fifties, I thought I did. All innerspring mattresses were padded on both sides and never thicker than seven or eight inches. Latex was usually four inches, rarely five, and almost never padded. Mattress ticking was almost all cotton and most mattresses were made with dozens of metal buttons attached to cords under tension that went to the opposite side. All box springs had real coil springs. Choices were very limited. I soon became aware that customers who had no real way to determine quality seemed to value thicker and smoother mattresses more than thinner and tufted mattresses.
I convinced Sealy and Simmons to make slightly thicker mattresses to my specifications as exclusive items for my growing chain of sleep shops. We displayed the nationally distributed Posturepedics and Beautyrests next to our own Sealy and Simmons smoother and thicker mattresses at no price premium. Customers voted with their pocketbooks. The lesson was not lost by our suppliers and the race to the fattest slowly started and shows no sign of flagging.
Sagging, or body impressions, the major mattress problem sixty years ago has only been exacerbated by the exuberant use of excess layers of padding in this century. Innerspring coils have remained only five or six inches tall at most, so all the extra thickness is usually some form of foam and synthetic fibers. The first night the bed is used, the padding starts to compress under the weight of the occupants. The process is continuous, but fastest in the early years. More padding, especially low density foams, equals more sagging and impressions and unhappy buyers. Decorative quilting helps by compressing some of the padding on the surface, but only the use of expensive dense padding can minimize and slow down the body impressions. If your new mattress is one sided, unless truly high quality materials are used, life expectancy is minimized by the extra thickness of the usually low density padding used.
This problem will not be solved in the foreseeable future because the single sided mattresses can be much more profitable for the makers. Virtually all innerspring units made in the United States come from one maker who has no incentive to invest in new machinery in competition with China.
The ideal mattress for most people has individual pocketed coils and is padded with sufficiently dense foam to resist sagging. More than eleven or twelve inches in total thickness, measured from binding to binding, can be a costly mistake. You can visit Charles P. Rogers Beds, to see how a 155 year old American company properly makes old fashioned mattresses using contemporary materials. If you are on the other side of the pond, a good source for mattresses is Dreams. You can always email me at oldbedguy@gmail.com to get straight answers to any bed or mattress question.