[CompleteSkeptic]

State-of-the-art results no longer require unsupervised pretraining with autoencoders or RBMs, but back when unsupervised pretraining was more popular, top researchers were rationalizing that it was consider more biologically plausible than the standard nets trained with back prop, since brains generalize through observing a large amount of data over their lifetime to quickly recognize new objects and since the nets aren't trained for a specific task, they would hopefully generalize better and be a step closer to general intelligence.