One part of securing my data, beyond backing it up, is to have it on another disk. May not make sense, but that’s one of my reasons.
I could partition a disk, but I like an external drive having a different drive letter. Again, may not make sense, but that’s one of my reasons.
As for the hub, it does affect the esthetics of the machine, but in my opinion, it’s okay. The hub I’m looking at is pretty tight and I see no reason at all that it would be unstable.
As for cost, 1T, per your example, is still cheaper but look at a 2TB. It’s a $600 add on.
It really falls into being something that is the way I like doing it. There is a cost savings and I’m not tied to the esthetics quite the way you seem to be. I think my proposed option is cleaner than having a wire to the back of the machine leading to a portable disk or even worse, a separate hub on the desk or hanging off the bottom of the screen.