I’m sure there are people aware but for the laymen this is such a massive vulnerability.
This is only a vulnerability if you suspect a threat actor might physically access your computer. For most people, this is not a concern. There’s also the issue that it has processing overhead, so it might make certain operations feel sluggish.
Encryption is not a panacea, because if someone ever forgets their password (something common for the layperson), the data on that drive is inaccessible. No chance for recovery. Certain types of software may not like it either. It’s one of many considerations someone should make when determining their own threat model, but this is not a security flaw. It’s an option for consideration, and most people are probably better off from a useability standpoint with encryption disabled by default.
Physically remounting a drive is the same thing as just plugging in a USB and going to town. Instead of taking the drives to a different system, you’re bringing the different system to the drives!