It is not unreasonable to speculate that MtGox could be using their apparently intentional manipulations to buy coins cheaply from their own trapped users and then selling them on external markets to generate huge profits. Or just to obtain more coins cheaply to recover losses due to seizures. This could be their strategy to try to become solvent again.

There is potentially insider trading fraud brewing at exchanges. Another attack vector for government regulators in the future ex post facto. Coin taint becomes a serious issue down the road ex post facto.

What users should (but the masses will always be blissfully gullible) be learning from this is that any centralized balances are evil. Placing your balances in the hands of third parties means effectively government has complete control and can destroy the apple-cart with regulation and seizures at-will.