All voting systems have pathological cases. The question is how serious they are and how likely they are. There's a tendency for people to look at one of these cases and think that it is disqualifying, but that's not the right approach. One should look at the whole picture.
Approval voting is a special case of range voting where there are only two values. For small numbers of voters, adding more values to choose from will help prevent the pathologies. For large numbers of voters, that's not necessary -- the statistics make it extremely likely that you get the right result.
Every AV voter has to decide where their approval threshold is. For a candidate that they're iffy on, are they going to vote for or against them? If everybody has exactly the same threshold, then yes, pathologies become more likely. But in reality the thresholds will have some distribution, such that a candidate that everybody is iffy on will tend to get voted for by about half the people. If no other candidate tops that, I think you'd be hard pressed to argue that AV returned the wrong result.