Assuming we need some kind of government, then does "against all" actually offer an improvement over the current system? The economist Kenneth Arrow suggested something in the opposite direction, approval voting, where the voters get as many votes as their are candidates, so the voters have the option of voting for everyone except maybe the absolute worst. Arrow did the math and liked the results from such a system of voting. And also, what is the goal of voting? Is it to give an individual an avenue for self-expression, or is it to achieve the social goal of forming a government? This is the argument against self-expression:
That arguably makes vote splitting worse. Do you cast your vote for the least bad corrupt candidate so the other candidate that wants to [legalize killing babies/control women's bodies] doesn't win, or do you vote for the "against all" option so that both corrupt candidates get disqualified?
Then approval rating would mean something.