Indeed I know we've seen blocks trigger the penality, but we haven't seen a movement out of the median.
We have on multiple occasions. Not with the sort of smarter algorithms that ArticMine discusses though.
I'm not sure I agree we can ignore miner optimization. Such behavior may affect the overall incentives. Transaction creators and miners are in a sort of conversation, with fees as the language. You probably can't understand one side of this conversation, or the conclusion of it, without considering the other.
miner optimization as in miners creating better algos to include transactions in blocks to reap most reward?
So this gives us some choices - we either think of the most optimal block inclusion algo based on the parameters set in place by the auto-fee adjuster (can we give this thing a name?), or we make the auto-fee adjuster parameters such that gaming them doesn't totally bork the system.
edited to add - so its engineering perfection vs. fault tolerance.