I don't think I would like such a system that maps everything directly to memory. At least, with the current separation, if some program's or even the kernel's

I don't think I would like such a system that maps everything directly to memory. At least, with the current separation, if some program's or even the kernel's memory gets corrupted, I can just restart my computer and it will usually fix it, whereas using an NVRAM in such a way could make it easier to break things in a durable fashion.