Wouldn't solve the weirdness of an easy-to-process overworld material being stronger than a completely manufactured material predicated on quite a substantial amount of research. It's just not at all an interesting material or process. You're literally just throwing shadowmetal and primordial pearls at it until it's better. All the addition of warpwood rods would do is push the problem further up the pipeline.
Well, it wouldn't make them obsolete. It's kind of hard to obsolete something when there's nothing better. Yes, it would be pricey, but that would be the point. It gives you something to do with you're resources when you're end-game and have the resources to spend. And if you look at my post above, it's actually quite a substantial upgrade.