the motivation for soldered everything is profit margins and the ripoff prices for upgrades.
Not security. There is no additional security here
Not security. There is no additional security here
You can't just physically remove the SSD from the machine, place it in another and brute force the encryption.
It's another story, a part of the encryption is stored in yet another place on Macs, which it'd be still stored there if the SSD could be moved in/out.