If you simulate a body with the same inputs as the existing brain, do you just have a "faster horse" problem, where you have a brain that could possibly perceive/process information faster (or slower) than a real human depending on the speed of the simulation? That could be useful, but sounds potentially rather bleak, especially if we limit what it can do to change its environment. It also seems limited for e.g. central planning - it can do planning faster than any individual, but likely will still have working memory size limitations, if it's just a simulation of a human brain. So it may not be so much better than parallelizing tasks across a bunch of humans.
More interesting, probably, then, than the "super human" style, is giving a new sort of intelligence different and additional senses, so that it doesn't want or need the same sort of physical embodiment we have, a la the "set sets" in the Terra Ignota series. But then we have to figure out what separates abstract intelligence from our own senses, and how to usefully augment it with new senses for a data-based world...
There are plenty of things that can't (or can't efficiently) be represented in a single agent.
This is (for example) Hayek's main critique of central planning: "[price] understanding cannot occur in an isolated computation or behavior"; there are simply too many necessary details to fit into any one head/computer, and therefore we should prefer markets. (Markets being definitionally not located in any one isolated computation/behavior, but inter-agentially in lots of them.)