It is highly suspicious that before that particular reward, soulboost gives materials needed to upgrade thornbreaker, and after it gives materials needed to upgrade silversteel, but the middle step is just not there. This looks like KR just forgot to modify our upgrade cost from TB9->IA3, because this is where the otherwise coherent story breaks up.
On the other hand, there is nothing wrong with letting people experience a little bit of material gathering, especially since during this even you can literally fish for PTS, and there's no harm in crafting your own empyrean stones. It just tells you to play the game a little bit more.
I do, however, disagree with our CM's statement that this is "intended". It clearly is not. Why give bound PTS, when they are 100% useless, especially in context of rewards before and after? Just no. KR forgot to change the price, whatever, just don't tell me it's "intended". Find a different way to say "just deal with it", please.