Currently this is the weak point of using external bootable SSD's. Because of that, I prefer the SSD's where the Thunderbolt/USB cable is captive at the SSD end, as then there are less connections that can be unplugged accidentally.
What I would like is to have in the laptop a CFexpress memory card slot.
The CFexpress memory cards have a PCIe electrical interface, but they are mechanically identical with the older Sony XQD cards, i.e. they are solid, rugged, not flimsy like the SDXC memory cards, and they allow a very large number of insertion/extraction cycles.
If the laptops would have such card slots and if SSD's would be available at a reasonable price in this format, then there would not remain any reason to use non-removable SSD's. The current CFexpress specification is based on PCIe 3.0, but future versions can be updated to PCIe 4.0, like the internal M.2 SSD slots of the latest laptops.