Doesn't the mine boss drop like 10 shards?
the adult poptop?, yeah it does. however, the other 10 have to be found on the containers scattered all around the place. and sometimes the procedurals dont generate a mine big enough or with enough filled containers for the 20 shards.
reducing the number to 15 would suffice IMO.
however. the real deal would have been to make the underground more interesting. it would give a meaning to reach the magma layer and get the shards.
but you cant do much with them outside of activating gateways and making explosives, and upgrading the forge.
the underground of every planet is practically full of biomes that dont have many interesting stuff aside of a few chests. no interesting resource to extract from them most of the time.
and metals are very lacking most of the time, you would expect that as you get deeper the ore clusters become massive. but doesnt always happen. they look as scarce as in near the surface.
i dont know if its due to getting used to the Terraria way of having each planet biome extending to the underground and each one having its own unique features.
then having minibiomes that help to cover the big layer of dirt and stone.
Terrarian worlds are choked full on granite and marble biomes, with underground cabins, then mushroom biomes, mossification, large clusters of metal reaching the underworld and aquifers that challenge you to to either get breathing equipment or mine your way around them.
in Starbound the starting planet has a big layer of ground, then usually a desert layer under it. and then caverns. yeah there is the usual mineshaft or sandstone location but they barely have stuff.
there's almost no water down there, and ores are from scarce to mediocre amounts of it. (unless you reach Tier 4 planets which have to have much more larger deposits. but even then).
and each minibiome just adds unnecesary amounts of material to take care of because its useless for your basic needs. they only serve for building stuff which isnt your main priority right now.
and of course. each underground layer in Terraria adds crafting stuff that you dont find on the surface. on the starting planet the most you get is hardened carapace, venom sample and living root.
sometimes the desert spawns "mechanical" type mobs which give static cells or the like.
but most of the time if its not an RNG monster, its a unique mob that you can find on the surface.
i know the game encourages you to explore other worlds instead of staying in one
but right now there's not enough content to get you hooked on underground exploration. you only go down for the ores which are always a dire need, unless you're playing survival which in that case you easily get food on any planet.
i would be more hooked on getting those core fragments if getting to the magma layer was an interesting endeavor.
much like searching for Adamantine Spires in DF or reaching the Underworld in Terraria for the hellstone ore.
you dont see that in Starbound (yet)...and its a shame.