I know my reaction was similar to the crowd, but even so I recognize that it's the wrong thing to look for. If Arc's initial release state could be summed up as "Lisp with some cleaned-up and rearranged features," then it's really not that different from say, Digital Mars D, which is best described as "C++ with some cleaned-up and rearranged features." The difference is, D has a massive compiler backing it, and its scope is unlikely to change. Arc's minimal implementation substance only makes it easier to change tack midway.
I've only gradually learned to restrain my sense of ego and take a similarly minimal approach with my own projects(indie games) - my newest process is to always start the final implementation with a text console interface. Besides encouraging better architecture in preparing for a later graphical interface, it's easier to debug the key elements this way than to have "stuff moving on the screen" at 30 or 60FPS and get frustrated figuring out which of those frames is the one where you're getting an error, let alone what routine is causing the problem.