This is because the network fundamentally operates with token holders owning part of the network bandwidth. Therefore anyone wasting tokens by doing nothing with them is wasting electricity and hardware. If you're holding tokens - at least rent them out to dapps
If you don't rent out coins and you waste valuable hardware and electricity - why would anyone want you holding tokens? You're essentially killing your little bit of the #EOS network. I believe that's the argument for @dan or whoever adding this law.
However, I believe the law should be changed to that if their coins aren't touched for 3 years - their tokens are automatically rented out to dapps so that the person doesn't lose everything - he would actually make money and also because he won't damage the network.
This makes absolute sense. There is a cost to storage, just like storing gold ingots costs money, so should tokens in my view.