OK, I somehow undeservedly sneaked in with that answer. I had totally forgotten about Hodgekin's Law of parallel planet development, but I subconsciously applied Roddenberry's Law of parallel plot development.
Clue #1 In this episode, there is something new. We've never seen that before, but it serves a useful function for the viewer. Why did they not also add something more utilitarian? For example, what about that something which shows up (apparently) new in later episodes? ... Well, it takes a lot longer to make one of those, and what would have happened to the urgency that was so needed in a good plot?