I see that there is some unclarity wrt fees and rewards.
In payment network there are fees on transfers. Those pay the rewards and fill the same function as store cost.
If SNT in data network will have a fee on transfers is not decided. The aim has been to have it free. Naturally there must be a hinder to abuse. If client extra-work is not enough then something more is needed. Whatever the solution will be, it will of course be addressed.