Apart from having more storage capacity, why not just get a complete portable one that uses 5V and doesn’t requires you to power it with a plug? What advances does a big 12V external hard drive have against a smaller fully portable 5V HDD?
I have a Seagate One Touch 5TB and it’s great but I want another one probably with more storage but from what I’ve seen only Seagate’s Expansion Desktop drives offer more storage than 5TB.
Speed and Capacity.
On your same logic, why use USB when you could just use a NAS instead? You don’t have to plug anything in.