Terraria is fun because its progression is not as deterministically tiered, and the aftermath of the progression is persistent. Nominally, everything you can find in the game can exist within the one world you generate at the start. What tiers exist are generally locked behind progression triggers for good reason, and there are often shortcuts available, in true Metroidvania fashion, that allow you to cut through a more difficult area to better tier equipment, and consequently keep visiting the previously impossibly dangerous areas with impunity as your gear improves.
Starbound is a... well it's a sandbox of course, but I think a desert would be a more fitting simile. You do progress, but the trail of your progression is erased as you go along. As a result any planet you visit as you travel will lack the same buildup of character that a single world of Terraria has. On top of that, the tiers that exist are locked away thematically, running against the game's basic premise as a Metroidvania, and shortcuts do not exist. You will never find a tier 1 lava world, for instance, and the heat-resistant suit upgrade is locked to a quest requiring you to have a particular tier of equipment, so it does not matter at all what tier the lava worlds are.
Starbound's potential is in being a survival game, where every world has things to offer, but any world can be anything, and good worlds may be hard to come by. It needs to be deeper, much deeper than it is now, in order to escape being a glorified 16-bit platformer with a crafting system and a bland galaxy as a backdrop.