What I still don't get is why they haven't opted to include several different types of VLS on ships like the 055 to enable the fitting of a bunch more cells like many other navies do. I.e. a portion are the largest CCL UVLS that can accomodate the YJ-21 and the other largest missiles, and the rest are some smaller version that can hold a more slender selection of missiles (but not the HQ-16 VLS). Or even a mix of 3 types. You're not going to allocate all tubes to hold the largest missile anyway so having them all be that large seems like an inefficiency.
You said those bolded sentences - But I would say that
those 850mm UVLS can actually be made to multi-pack smaller missiles (RIM-162-like MRSAMs, for instance). In fact, we do know that the PLAN is actually looking into multipacking capability for their 850mm UVLS cells in recent years.
Besides, there is always the
potentials for smaller missiles to grow bigger following further development and iteration processes. Why even cut off those growth routes with smaller VLS cells just for the sake of being able to have more VLS cells - And solely for that specific time period?
Using varying different diameters of VLS cells for just one warship would also repeating the same mistakes that the Soviet surface combatants had. That is, literally handicapping one of the very advantages of having a universal-diameter VLS design, i.e.
flexible missile loadout capability. With 3 or more types/sizes of VLS cells on a single warship, that's pretty much impossible to achieve.
Moreover, for ship designers, there is more than just VLS cell diameters to consider - Namely the
cell depth. No matter how big or how small the diameter of the cells are, the length of the VLS cells are also constrained by what's located underneath the cells in their respective sections of the warship.
Furthermore, doing so would be
unnecessarily (over)complicate the designing, manufacturing, logistics and maintenance. Imagine the workloads required to deal with three or more seperate systems of VLS, all on just one warship. Then multiply that across the entire fleet.