Hi Crock,
For some people an innerspring support layer just seems to work better than other combinations and it’s just that some people are built differently or respond differently to certain designs than others. In many cases it’s not really possible to go to the depth of analysis to even be able to identify why but post #2 here has some information about the difference between an innerspring and latex support layer and how they respond. Some of the most knowledgeable people I know in the industry that could sleep on anything they wanted sleep on an innerspring latex hybrid. Of course the same could be said for any other high quality mattress because there is a huge range of different preferences and body types.
Phoenix