Arms is double extra especially not getting the open dev treatment because we've had several rounds of this happen:
"I have a brilliant idea!" "Well, lay it on me." "Okay, it's like this." "Holy shit, that IS brilliant. OK, let's write some artifacts and see how it shakes out." *Artifacts are written* "Okay, we kind of ran all the potential this had dry after two artifacts, and the second one shows serious structural issues. We need to scrap this and do something else." "Yeah. But I have another idea. It's like this--" "Holy shit, that's really clever." "Yeah but it has this one problem." "Well, we can probably work that out, let's mess with it." "Okay, we've burned three weeks trying different things and that core problem appears insoluble." "Son of a bitch. Back to the drawing board."
Or, in short: Martial Arts Techniques taught us not to preview things until we are positive we can deliver them.