Copyright duration is not really a factor in the FSF’s actual goal, which is for software to be distributed with user-modifiable source code. Copyleft licenses are a means of achieving this through the existing copyright system with its ludicrous durations. But making copyright terms much shorter would help, yes, because any released source code or even binary files could be used, reverse-engineered, and modified without permission.
Even if you reduce copyright to a year, it still requires waiting through that time before you can actually use the code. And even if you were free to use Windows’ source code a year after release, it still wouldn’t give you access to the source code itself. Meanwhile Microsoft would be free to use any GPL code a year after its release without worrying about any licensing requirements, since they have the source code freely available.
