My personal opinion (well, why i stopped being interested) is when the server went closed. Don't get me wrong, I have nothing wrong with closed source (i think i was "shihan" back on the old forums but i cant remember). I submitted one patch for the previous OSS core. But thats not why i'm no longer an active member.
I still stop by to see how its progressing and for me alot of what im interested in the hackability of the thing which is hard to explain so i'll give an example from when dolserver hit the streets.
When dolserver first came out I was very keen to try it for all the reasons anyone likes using server emu's. But its also something you can be actively involved in (unlike its sister project coad). The first thing I did when the code was good enough to login to was code up a auction merchant in its internal scripting language. That led to other things like the developer adding new hooks in the scripting language and so forth. In short, i was able to participate (as in have an impact on the project) without being an active dev for the project and still actually coding (now and then) for it.
I guess what im saying in is its hard to comment on vapourware (not that this is entirely vapourware, but its something the "users" really cant touch). The question "What do you want to be able to do in the scriptable npc's" is hard to answer because the answer is (in broad terms) obvious and hard to define in finer detail without actually seeing how coding an NPC would be like.
Lets say you coded the scripting engine such that it had 4 hooks:
1) when someone talks to it
2) when someone attacks it
3) when someone comes within a certain range
4) when someone leaves a certain range
Obviously this is very limited, but its a starting point, so users downloaded the source, get it running, code an npc and then find "ahh, we need some state information because this guys giving a multi-part quest".
Again, thats only a small example (of one particular component of swgemu) but it illustrates what im trying to get at and im sure im not the only one who feels that way.
Again, im not saying SWGEMU should be OSS, im just saying its the reason i personally have stopped hanging around (which is probably a good thing anyways
)