As a consumer I can only agree with what you are saying. Software that is provided free of cost can be extremely difficult to pay for in the future. I think the developers of Paperpile did the correct thing by charging money from day one. Of course there is a case for differential pricing based on the region of origin too. $5 is not the same in US and India and if a pricing mechanism could be developed that took into account the purchasing power parity it would encourage global adoption of your software too.