I was under the impression that upgrading from 32-bit to 64-bit required a new kernel. This would mean replacing the kernel is all that would be needed. Perhaps drivers and libraries need to be updated as well, right?
That could also be done in a non-destructive fashion. But all the other software does not need to be 64-bit specifically compiled does it?
So what then precisely, is the technical reason, why upgrading to 64-bit cannot be done without reformatting with a one-click approach?