Hey,
For you, what are the advantages of a Universal-VLS ? I can't think of any major positive aspects of having a VLS capable of firing every types of missiles compared to a panoplie of VLS with their own missiles.
Growth. Versatility. Standardization. Larger VLS makes all three things possible.
Let's take growth first.
If the missile becomes obsolete, so will the VLS and the entire ship, and you will need to replace the VLS during its midlife refit. Small cells means small missiles, which will stuck you with short range missiles.
Let's take versatility next.
The bigger the VLS, the more things you can put on it. Those VLS dedicated to smaller SAMs can't be used with ASROCs, antiship or cruise missiles. So our frigate would need dedicated launchers for the ASROCs, ASMs and CMs.
Let's finally take standardization.
Frigate A class uses a VLS different from Destroyer B and so they both fire different missiles, and their munitions are incompatible with each other. This is a logistical headache for one ship to return to base only to find munition stocks available for the other ship.