Well, it's a few more cents on the bill of materials and some PCB real estate, and constrains the enclosure form factor. Ethernet ports have a transformer (or

Well, it's a few more cents on the bill of materials and some PCB real estate, and constrains the enclosure form factor. Ethernet ports have a transformer (or some other kind of electrical isolation) inside as well, from memory. Making it an add-on means you can spend more on higher quality electrical protection so it actually keeps the rest of the terminal safe, for those who need wires. And you can replace the add-on when mechanical overstress (aka tripping over the ethernet cable) is applied.