We add a healthy margin of error to our games' requirements, because current operating systems have considerable requirements themselves (especially with a ton of stuff running in the background, which is usually the case nowadays). As far as I understand Republic was compatible with Windows 98, and I assume the 800MHz (etc) requirements applied to a Win98 system.
The bottom line is that we don't want to add original system requirements if they're below the recommended requirements of modern operating systems.