I'm not advocating they "vanish" just that they be redistributed to active bitcoin participants. That's all. If an address has no activity for a certain amount of time, it's pretty sure that it can't participate in bitcoin anymore. And that it won't be.
Now as far as secondary storage to me that seems like a very slippery slope. Where they can segregate utxos based on some type of metrics and charge them extra fees to use bitcoin. So what ends up happening is that bitcoin is not really fungible and certain kinds of utxos will be discriminated against. I wouldn't be interested in that at all.
But if someone is not going to use their bitoin for their entire lifetime and another lifetime after that then a case could be made that they dont need it.