WHYYYYYY?
What the actual FUCK is the point of having the highest-end chipset and not having its PCIe lanes exposed via the PCIe slots? I don't understand what universe that MSI lives in whereby users are going to have 4 NVMe SSDs but no secondary PCIe card.
If the manufacturers want to put 20 billion NVMe slots on their boards, that's fine. Just also add circuitry so that the PCIe slots by default have all lanes allocated to them, and every time you plug in an NVMe SSD it steals 4 of the slot lanes. So you'd start off with an x16 slot, then it would go down to x12, then x8, then x4, and finally x0 with 4 NVMe slots populated.
If that's too complex (and apparently it is), just go with the solution that everyone knows works - a separate PCB that can house up to 4 NVMe SSDs and plugs into a PCIe x16 slot.