Good point, but I think it's more general than that: A brain in a vat's need be in a particular location is significantly reduced. Interaction with remote things is limited only by light speed, and possibly bandwidth.

Travel costs for brains in vats are significantly reduced. Not only is travel cheaper monetarily, but the experience of travel can be completely hidden. Instead of sitting in a seat and looking out a window, you could spend your time in a VR world or interact via robots. The only reason you would want to stay in one place is to interact with the nearby environment at low latency.

In the end, uploads are the way to go. You can run them faster and travel cost is just data transfer cost.