i like the idea "especcially the key mold as autofarming them might take up to 3 days in a row *truestory*"
and about you worrying about people playing the game in that way, i tought about it, the only thing i can think of is a new mechanic that will only let you get certin items according to your progress, like before defeating any boss's , you can only get X items from fishing, after defeating eye of chutulu you advance making you able to fish for X and Y items, same for skeletron and eater of worlds etc... like a package of fishing content that unlocks only after doing a certin thing, this way players wont be able to get somthing so much more advanced than thair current progress ingame owo.
and about pandoras box, i wish that it could only be opened in hardmode underworlds only, and the moment you unlock it spawns monsters (as you said) in certin patterns , like 12 packages, depends on your luck, as waves of monsters,(maybe even a boss at the final wave!) aftr beating all of them, a message would show up like ( the power of chaos has been controlled ) and you will be able to open the box, containing items, yes i know how u said u dont realy want items in it, but that will be less interistig aftr going trought all of that, besides in some games i have played that contained the pandoras box they did use it as a strog weapon itself, like in devil may cry 4 owo.
