Having a fail-safe functionality (vs ... fail-deadly, I guess, with no fuse) is critically important (far more than just being a good idea), but there's no reason it can't be a circuit breaker with feedback to the computer system. Self-resetting would probably be a bad idea (if there's a short, you really do want it to stay off), and even having computer control of it would be questionable (although if the control system met DO-178 standards, it'd probably be fine), but even a simple feedback mechanism would be a huge win. For that matter, there's no reason that the computer can't tell you what fuse is blown, what it affects, and show you where to replace it.

Here's the real deal: a fuse costs cents, and a breaker costs dollars. Fuses rarely blow, so increasing cost two orders of magnitude for an extremely minor benefit doesn't make a lot of cents (har har har). Even Tesla cares about cost control - imagine if the whole car were two orders of magnitude more expensive. I expect that a feedback mechanism would probably actually be cheaper than breakers, since it could be a single, cheap chip rather than expensive mechanical devices.