Hiro is messing around in Flatland. He is doing this partly to conserve the computer's batteries; rendering a three-dimensional office takes a lot of processors working fulltime, while a simple two-dimensional desktop display requires minimal power.
But his real reason for being in Flatland is that Hiro Protagonist, last of the freelance hackers, is hacking. And when hackers are hacking, they don't mess around with the superficial world of Metaverses and avatars. They descend below this surface layer and into the netherworid of code and tangled nam-shubs that supports it, where everything that you see in the Metaverse, no matter how lifelike and beautiful and three-dimensional, reduces to a simple text file: a series of letters on an electronic page. It is a throwback to the days when people programmed computers through primitive teletypes and IBM punch cards.
Since then, pretty and user-friendly programming tools have been developed. It's possible to program a computer now by sitting at your desk in the Metaverse and manually connecting little preprogrammed units, like Tinkertoys. But a real hacker would never use such techniques, any more than a master auto mechanic would try to fix a car by sliding in behind the steering wheel and watching the idiot lights on the dashboard.
Hiro does not know what he is doing, what he is preparing for. That's okay, though. Most of programming is a matter of laying groundwork, building structures of words that seem to have no particular connection to the task at hand.
He knows one thing: The Metaverse has now become a place where you can get killed. Or at least have your brain reamed out to the point where you might as well be dead. This is a radical change in the nature of the place. Guns have come to Paradise.
It serves them right, he realizes now. They made the place too vulnerable. They figured that the worst thing that could happen was that a virus might get transferred into your computer and force you to ungoggle and reboot your system. Maybe destroy a little data if you were stupid enough not to install any medicine. Therefore, the Metaverse is wide open and undefended, like airports in the days before bombs and metal detectors, like elementary schools in the days before maniacs with assault rifles. Anyone can go in and do anything that they want to. There are no cops. You can't defend yourself, you can't chase the bad people. It's going to take a lot of work to change that -- a full-on mental rebuilding of the whole Metaverse, carried out on a planetwide, corporate level.
In the meantime, there may be a role for individuals who know their way around the place. A few hacks can make a lot of difference in this situation. A freelance hacker could get a lot of shit done, years before the giant software factories bestir themselves to deal with the problem.