While I now mostly agree with you that there is more unsafe code than there should be, I still maintain that the frequency of unsafe in a deptree is usually still small enough to be practically auditable, ignoring FFI. It could/should be much less, but it's not too bad. I've done such audits a few times and it's not been too hard and taken very little time.
Auditing FFI is a whole other challenge, however :(
Well, yeah, but you don't really download Rust binary libraries yet :)
You do have C libraries which you access through FFI. This is inevitably unsafe. We should be auditing more there. Though IMO it's still manageable, for most crates.
Auditing FFI is a whole other challenge, however :(