I'm not sure, if a miner holds many coins they are inclined to leave as many as possible sitting idle so that their mining rewards in 10 years are higher. Anything like this can be gamed too easily.
If you leave coins idle past the shelf time, you get diluted. It's an incentive to move coins. Incentives to move coins are good for the economy. As I see it, there is no downside to the game. It's just a question of how much win there is. (Probably one would cap the maximum emission, so that massive hoarding would not be incentivized.)