And what would we do when we run out of such coins to "steal" and pay miners? It is a finite number after all.
In the year 2140 we start stealing the coins which have been not moved since January 2009.
In the year 2144 we start stealing the coins which have been not moved since February 2009.
...
In the year 8428 we start stealing the coins which have been not moved since January 2140.
...
The same problems apply here.
We can't decide what people should do in a hundred years from now when we aren't even around.
You also significantly decreased the incentive and also re-introduced a decreasing reward since the amount of coins "lost" or amount that hasn't moved in a long time is decreasing per year as price goes up and more people get in. That means after a couple of "periods" we could theoretically end up with a fraction of bitcoin as the total amount "lost", which is like halving all over again.
At some point as you keep increasing the complexity of this idea, it raises the question of why not just increase the supply in the year 2140?