You are mostly correct. Consider the strongest Tesla at 581kW. Assuming we do the same in one 48VDC motor we are talking more than 12kA !! Even more on the AC motor side. Even ignoring the massive wires (well bus bars) and converter costs, I don`t think this would be any safer than any higher voltage system, which is the general reason for going 48V.
I`ve tested short circuits with 24V systems with 100A capability, and the arc is scary as fuck without a contactor to do the contact. I did it once by hand thinking it was safe, got a huge fireball as plus hit ground, bounced it slightly before reconnecting and the wire caught fire and welded stuck surprisingly quickly. With 12kA nominal capability I can`t even imagine. And the di/dt effects of parastic inductance could make all kinds of interesting effects
That said, for a low end hybrid I can see it work. For instance a 16kW system with 400A could be doable.