I'm not sure what the use of it would be. That sounds extremely niche to me. I mean, how many people join a hardmode world with a completely new character and how many players in multiplayer won't get some basic gear from the other players? And if you do go into a hardmode world with a new character, hellstone can be destroyed by bombs and dynamite, so molten gear is available even to new players, even if the lava makes it somewhat risky to mine.
It really doesn't need to be pushed that far back in progression to justify returning to its original pickaxe power. Just make it post EoW/BoC and it won't really skip anything.
That aside, the gold/platinum pickaxes are actually better than the current Reaver Shark due to their faster tool speed.