From a dev point of view providing official modding tools is a bit of a nightmare. When you provide official tools you add a whole other layer of needed support and the game design is actually more complicated as you need to leave various hooks open for that modding support.
Sure they would have to offer some level of support for the actual modding tool but once they have it up and running and bug-free (I know - Larian) that is as far as support has to go. Even documentation doesn't have to be encyclopaedic - look at Bethesda and the CK for Skyrim.
I think your wish for an adventure creature might be more of a runner - something like the Solasta games maybe.
