In other words, a system where coins that have not been spent recently are worth more? I suppose you could do such a thing, but it doesn't seem useful; typically friction in economies is a bad thing.

But I imagine you'd price things just like in any other market: supply and demand.

Isn't it just how Proof-of-stake altcoins works? In those systems, your wallet amount grows as the time passes. Ie: 10% over a year. I think this is very similar to bitcoindaysdestroyed-coin.