Hi charlestonbedding,
While it’s certainly “safer” to choose a mattress that is a little too firm than too soft because you can always “fix” it with a softer topper … and I also agree that a mattress that is too soft can create just as many issues as a mattress that is too firm … I’m not so sure I would agree with your main point that “firmer is better” … especially for side sleepers … or at least I wouldn’t make it nearly as general.
I understand that rotating the pelvis or the shoulder can increase the surface area of the pressure point and relieve pressure … but it can also lead to rotational alignment issues that could be solved with softer pressure relieving layers that are suitable for the person on the mattress without having to learn to change their rotational alignment to “accommodate” the firmness of the mattress.
There are a few forum posts that mention or discuss this including post #6 here and post #2 here and post #6 here and post #7 here.
I certainly appreciate the thoughts and insights but I believe that taking what you are suggesting too literally could lead to some poor mattress choices so I wanted to add some additional thoughts and information to add some “counterbalance” your comments as well.
Phoenix