The instability is a major killer from my experience. Reminds me of the Neverwinter Nights 2 toolset.
I see no major problem with the steep learning curve. Chances are there will be gamers who are also professional programmers that can figure things out and just blog out the process for the rest. I've worked with research softwares that have undocumented capabilities which leaves the user figuring out things for themselves. IMO this is not a serious stumbling block.
If you have a dedicated fan-base that's dying to mod the thing they will even hack a game which wasn't even intended to be modded in the first place.
added:
I gather that Larian is a small studio (I don't know if they've expanded). They strike the right chord and it is even possible that a group of experienced modders could even outshine them in some areas/categories (cinematic, gameplay, balance, imported assets... who knows).
Last edited by J747L; 12/06/15 04:14 PM.