I agree with some of your first point, but the second not so much. I think pg released arc as a first cut with one application baked in to act as marker for a stable version. Obviously I can only guess, but I also think he expected a larger community of interest, one that could take it to the next level. That never happened and with only a handful of keeners, 10 years later, the things you mention in your first point are non-existent or half-baked experiments. It's possible Arc may get there, and I hope it does, but at this rate it may take a hundred years. :)
More interestingly, though, shawn is bringing some interest back (at least for me) and making substantial changes that could breathe new life into Arc. I don't agree with the empty list - nil change, but the table changes and reader changes are good. I do think the more seamless the racket interop is and the more racket can be leveraged, the better. Clojure has good interop with java and that's what made Clojure explosive. If we can do that with Arc/Racket then we are better off for it.
"Clojure has good interop with java and that's what made Clojure explosive. If we can do that with Arc/Racket then we are better off for it."
Do we ever expect Anarki values to be somehow better than Racket values are? If so, then they shouldn't be the same values. (The occasional "interop headaches" are a symptom of Anarki values being more interchangeable with Racket values than they should be, giving people false hope that they'll be interchangeable all the time.)
I think this is why Arc originally tossed out Racket's macro system, its structure type system, and its module system. Arc macros, values, and libraries could potentially be better than Racket's, somehow, someday. If they didn't already have a better module system in mind, then maybe they were just optimistic that experimentation would get them there.
Maybe that's a failed experiment, especially in Anarki where we've had years to form consensus on better systems than Racket's, and aligning the language with Racket is for the best.
But I have a related but different experience with Cene; I have more concrete reasons to break interop there.
IMO, It would be better if arc had implicit methods that provide access to racket capabilities. In Clojure having libraries, name spaces, and a seamless interfaces to java translated into a plethora of libraries for Clojurians to utilize. Can we not do the same? Well if the goal is for "widespread adoption" then we need to.