Why are Oracle Separations Counted as Evidence toward Unconditional Separation?
At best, the evidence given is only heuristic and informal, but it is still important. Oracles in the examples you gave do address the general question: how does quantum computing compare to nondeterminism and randomness, in power? The oracles definitely do not answer the original unrelativized questions, rather they provide a different (related) black-box model where the question provably has a negative answer. Since unconditional lower bounds are very difficult to come by, oracles can be useful information, but again it's only heuristic.