[Tyhm]

No. Certain elements would hack the software they rented to never expire (golly, nobody ever cracks shareware expirations, I wonder how they manage?), to not connect to Graal's central computers, and to operate independantly. Then they'd claim it's their own game, let everyone on for free, try to run Graal out of business, then sell out to Microsoft, and suddenly our beloved game is another MS title.
That'd be bad.
I'd like it if there was a way to make a thin-server, something fairly innocuous that lets you share files from your computer to the Graal Main Servers, so they keep the heavy player-control software and you keep the levels, but apparently that'd be even less efficient than the current system - disk space is cheap, bandwidth is expensive.