If this complex behavior can be explained using only 302 neurons, I have no doubt that the complexity of human behavior and consciousness can be explained using 100,000,000,000 neurons.
If I start from the assumption that I am mistaken about what I think consciousness is--that maybe it doesn't exist at all the way I think it does--then I don't have to worry about how matter gives rise to it. I can focus instead on trying to understand where my definition went wrong.
Humans have never lacked for opinions or explanations about what natural things are, or how they got that way. But in the practice of science, these must yield before empirical evidence.
As you note, there is a huge amount of evidence that consciousness is physical. But there is no objective evidence that I experience consciousness as you define it. You just have to take my word for it--and so do I. But maybe I'm wrong.
It's true for the worm as well. You can't understand everything about the worm without emulating the other 600 or so cells, and putting it into environments similar to what biological worms occupy. The lego mindstorm worm is interesting, but it's hardly the natural state of the worm.