I'm not sure why people complain about digging for core fragments. You should be digging anyway; it's the only way you're going to find enough ore to get you started. You can find weapons and vanity items. A few times I've found oil, allowing for an early lamp on a stick.
I typically enter the Erchirus Mine with every base tech unlocked and at least a couple of found weapons, thanks to digging.
the complain comes in the form that in order to get spaceborne you have to complete a quest that doesnt even give you the materials completely. no, you are obligued to reach to the planet's core in order to compensante RNGisus bullshit.
now. i wouldnt mind going the extra mile to unlock the entrance to the outpost. but seriously, the underground is boring. the ore volume in the clusters is mediocre at best. and there's not much to get your interest in digging further deep.
do you see larger amounts of metals? not unless you reach a tier 4 system at minimum
do you see unique items? rarely, the only legendary weapon i've got in my playthrought was the alien worm gun that outside of the uniqueness its completelly useless
do you see interesting landscape? barely, specially in the starting planet. guaranted to have a layer of desert and clay. but nothing more. i've seen what seems to be jungle and found a large tar biome once in a toxic planet.
the only interesting stuff on them are the blocks. no special features like underground cabins or minidungeons. that only happens on the surface biomes.
again. i dray my complains because of Terraria. you can dig and dig and dig on a terrarian world and you're guaranted to find either large clusters of ore, a unique mob with interesting drops, a minibiome with plenty of stuff to loot or a cabin with a golden chest.
sometimes you find a mushroom cavern that gives some use in the form of making second tier potions out of the mushrooms. and its unique mobs.
the mob diversity in Starbound is horrible. most of the minibiomes only have 1 unique spawn. the rest of what appears above and under are randomly generated things that dont seem to have a feature related to their respective biomes outside of color.
and all of them drop the same stuff. is it an insectoid? then hardened carapace, is it half plant? living root, i can understand the homogenity of drops due to being the same type of monsters but at least the unique mobs should drop something that makes the biome worth looking for.
most of the time you find just a chest sitting there with randomize loot that its either cosmetic and useless, or its furniture that its also useless unless you want an specific colonists, which i doubt will be of help to your mission.
so yeah, there's plenty of stuff that should be fixed or expanded regarding the underground.
the game may entice the player to explore other worlds. but whats the point of it if every planet has the same boring stuff under its crust? you enjoy more travelling on the surface and going all the way around finding crops and settlements than trying to find stuff underground.
the only reason i go to the depths is for metals, because buying them from the Ursa shop is expensive and pixels are a pain to obtain if you dont do missions or loot everything on sight.
I started right after 1.0, and on my first dig down to hell, on my starting planet, I found a gnome biome, ice biome, and flesh biome, each with multiple distinct monsters. And I found tons of underground cabins; some in ruins, other functional with NPC's living in them, some of whom even give quests. Also I found a dungeon accessible from the surface without any digging which held the 20 core fragments I needed to complete the quest, and had a mini-boss.
It sounds to me like you are playing a very outdated version of Starbound.
i played 1.0 and just got 1.0.5
my point still exist. too much on the side of useless customization but not enough functionality. most, if not all the unique biomes in the game only reward you with furniture and cosmetics.
most minibiomes have only 1 or 2 weapons. the rest is cosmetic stuff that clutters storage for practically cero sense. and its already annoying that the weapons are rare in the first place. i've never found the gnome gun for example.
the amount of rare and unique weapons is also opaqued by RNG generic weapons that everyone can exploit right now with the T10 moons.
and even then all those randomized weapons lack variety. i hope the add more special habilities or something.
i dont know if its because im used to seeing less on the side of generic equipment and more on the side of broken as fuck stuff instead.
i mean, again, Terraria started the trend. the last common metal that you craft is gold/platinum. and its weapons are just generic without any kind of interesting deal. in fact, most of the craftable weapons lack any kind of speciality (hardmode excluded).
but then you start entering the special biomes and stuff becomes crazy. specially taking in account that the new craftables require you farm bosses.
of course there are still hundreds of unique weapons and items to be found in the underground there.
i cant feel that in Starbound. for time restrictions of the developers or anything.
no unique crafting for weapons. just generic metal stuff that will be never used because RNG generics have far more uses. even when you have to rely on luck to get the best results.
for this i say they should have sticked to the formula and add more flavor to crafting weapons and more unique weapons instead of adding procedurals to a system that really didnt need it.
heck, why even have 3 different anvil crafting stations if you're just gonna do 2 weapons? and even then they dont have any customization capabilities. that's garbage.