I'd rather talk about why the RNG is involved in crafting at all. I don't see raid bosses having a % chance to just not drop any loot at all. I bet that would get people bitching.
"But we had Ramuh Ex at 98% to drop gear and he didn't! the RNG is broke!!1!!!"
Actually Ramuh has a percentage chance to drop weapons, and Circus Tower has a percentage chance to drop Tomestones, Oils, and Minion. Not to mention the infamous Mirrors that Leviathan drops... So uh...
RNG in crafting is flat out statistics. Just get all your shit to 100% HQ and no more tears.