I assume that ontological security matters. If I know my consciousness runs on meat, I know that I have my own personal substrate. If I know I'm in the Matrix, I know that whoever has `root` access can alter or deceive me as they please.
The one thing nobody ever specifies about these crazy schemes, which would otherwise be a great way for humanity to get the hell off of Earth and leave the natural ecosystem to itself in our absence, is who will be root, and how he's going to forcibly round up everyone who doesn't like your crazy futurist take-over-everyone's-minds scheme. Hell, what's going to stop him from rampaging across the real Earth and universe, destroying everything in sight, while everyone else fucks around having fun in VR?
I'm really wondering why this nasty, insane idea has been cropping up more frequently lately in geek circles.
And that's not even starting into the sheer ludicrousness of claiming people's consciousness is pure software when we know that all kinds of enzymes and hormones affect our personalities!