For me the mechanic seemed to work. Using the mechanic seemed to give me about a 20% increase damage. And as for not being new, that really doesn't have any bearing on whether I like it in this game or not. I liked it, I consider it a positive. I haven't played S5 in quite a long time, so I forgot it was there. Was it spelled out in the same way?
And I think it was wasted, because you never ever had to consider your euipment, because the game is ridiculously easy. I am really surprised anyone really cared about that for a normal playthrough.
I think S V used an affinity system like with the elements. But I always thought this was used only for defense purposes.... Anyway - if the game really forced you to think about your party's equipment, this affinity thing would be a plus. On the other hand, it's so udnerdeveloped with only 3 "elements" and the only options are "weak to" or "strong against" (or neutral),so it isn't really fun imo.