I'm having trouble understanding why the success of pooling would be deemed unfortunate. Max-pooling or average-pooling are essentially learning something about a pair of contiguous features: while max-pooling saves only the most prominent/largest value, average pooling compresses information using the mean. Saying this is unfortunate from Hinton's standpoint amounts to saying that it is very unlikely to see any sort of pooling behavior at the level of neuronal populations. At a physiological and psychological level, what would pooling equate to?