Like with all other achievements, the free pack is given when the PSD Exporter is bought, to provide an additional incentive of getting it. When we gift packs to accounts that would otherwise trigger achievements, it wouldn’t award the extra free pack, since the packs were already provided for free. They are just there to give a better return on investment, but we can’t speak of an investment when everything came for free already. We thought that adding the Exporter for existing Pro members as a gift would be a nice gesture instead of asking them to buy it. In the latter case, the free pack would be awarded of course. I hope this makes sense.