I'd like to get some idea of what would be most useful to the modding community at this point. What kind of tools are you hoping to see in a "full toolset release"?
I think to sum it up, the "problem" that most serious modders face is that it's easy enough to modify and use existing things, but impossible to add new ones. A couple examples:
1) Additional pages to factories for more ship types. This likely falls under the engine hardcode, but for example a frigate factory uses both rows for frigates, but a capital ship factory can't be made to.
2) Entity types. Right now, there's no way for us to add new ones. We can't, for example, make a structure that has weapons *and* squadrons, because there's no entity type for one. Adding squadrons to the "weapondefense" entity crashes, adding weapons to "hangardefense" entity doesn't do anything. So we can't create a new entity, we can only modify existing ones with set parameters.
3) Abilities. Here we're also limited to only what exists. If we have a capital ship with 3 different weapons, and we want to make an ability to give one of them increased rate of fire, well, we're out of luck. The only thing that exists is "EnergyWeaponCooldown" and that's it. There's nothing for "PhysicalWeaponCooldown", there's nothing for any specific weapon type (BeamWeaponCooldown, MissileWeaponCooldown, PlasmaWeaponCooldown, etc), and we can't add our own.
I don't think anyone is looking for fancy GUIs or anything like that. Most people would be quite happy if we could actually add our own things rather than just recycling existing. There are some neat things possible to do with recycling, as evidenced for example by Uzii's mod and derelict ship graveyards and such, but it's still fairly limited.