Bumping version of dependencies doesn't guarantee any improved safety as new versions can introduce security issues (otherwise we wouldn't have a need of patching old versions that used to be new).
Maybe. But at least everyone being on the same (new) version makes things simpler, compared to everyone being on different random versions, of what ever used to be current when they were written.
If you replace a dependency that has a known vulnerability with a different dependency that does not, surely that is objectively an improvement in at least that specific respect? Of course we can’t guarantee that it didn’t introduce some other problem as well, but not fixing known problems because of hypothetical unknown problems that might or might not exist doesn’t seem like a great strategy.