Hi Sleepytime21,
This is unfortunately the norm in far too many cases and it’s because of the use of lower quality materials above the coils. There are some people who cut open their mattress and do “mattress surgery” and rebuild their mattress by replacing the layers that have softened or broken down and in almost all cases (including with premium mattresses) it’s the upper layers that have broken down. The best way to avoid this for those who prefer the feel and performance of innersprings is to make sure you know the quality/density of the materials that are used above the innersprings which usually means dealing with smaller independent manufacturers who fully disclose the details of all the layers in their mattresses so a consumer can validate that they are good quality and durable materials. Other options include component mattresses such as mattress/topper combinations or a mattress with a zip cover where individual layers can be replaced or having a local manufacturer rebuild the mattress by replacing the foam layers that have softened or broken down.
The “best” latex mattresses for each person are the ones that best suit your individual needs and preferences and personal value equation. It depends on the design and the type of latex you prefer. Some of the better options and possibilities in the greater Seattle area are listed in post #2 here. The key is always to deal with retailers or manufacturers that are open about the materials in their mattresses so you can focus on materials rather than brand names.
The Pure Latex Bliss mattresses and toppers at Its Bedtime use good quality materials but the toppers only come in versions that use very soft latex which is not always the most appropriate choice and PLB toppers may not be the best value.
Phoenix