You start off with high-speed trading (well, just arbitrage, as you said), then talk about how price of one commodity affects particular stock values. Then you say "Being able to cross-calculate these price changes also takes us a little closer to being able to plan the economy". But which price changes? The differences in prices that arbitrage exploits, or the correlations between fluctuations in one commodity and some other figures? It should be clear that the first kind of fluctuation essentially holds no information: I'd liken it to quantum fluctuations in a vacuum---it's meaningless, random, with any apparent information content just being an artefact of quantisation effects (in fact you can use the same language and say that arbitrage works because it exploits quantisation artefacts in different stock markets).
Lots of people, myself included, would argue that arbitrage doesn't really add value to an economy. You can argue for the "invisible hand", and that it's bringing the market in line with the ideal of perfect information flow but it's obviously not perfect or (a) people wouldn't be making money on arbitrage (how can it be perfect information flow if only some people are able to exploit stock/commodity data?), and (b) you've already mentioned that all this HFT can have bad effects as feedback loops (or "flocking"*) behaviour causes markets to go completely out of whack from time to time.
If, instead, you're talking about the web of connections and correlations between various stock and commodity prices, then you haven't established the connection between arbitrage or HFT algorithms and the ability to plan the economy. Quite frankly, that's a ludicrous postulation. Yes, I understand that you try to make the link by mentioning how algorithms are evolved, but consider:
* these algorithms aren't designed to build up an understanding of the economic system as a whole, but to exploit short-term fluctuations (including impulses deliberately injected into the system by buying and selling with a view to sending various stock prices in one direction or another). You literally can't see the wood for the trees.
* experiments with new models or new impulse triggers cost money--real money. You might argue that we can "evolve" better models this way, but in reality it's no different from a gambling addict pouring money into ever more complex (and fraught) betting systems. The only difference is that high-frequency traders generally aren't using their own money to fund these experiments.
* you can't account for (or predict) delays between an impulse and an observed effect. Eddie Murphy might have been right in his reasoning for when to buy/sell concentrated frozen orange juice in Trading Places, but he could just as easily have been wrong (it was just a film, after all). There's too much elasticity in time and in perceived value.
* there are too many hidden variables. If you can't even count the number of hidden variables, then how can you build a statistical model?
* all these mechanical traders are working in secrecy, so how are we to trust this as a means of economic planning (the "invisible hand" becomes a "shadowy hand").
* all these mechanical traders are also competing against each other, and they have no way of knowing (short of widespread industrial espionage) whether the observed changes are a result of "the market" responding, or simply a knee-jerk reaction by other trading bots. Again, hardly a sound basis for economic planning
Taking all this into account, your whole argument just falls apart. There definitely is something to be said for economic modelling that takes into account the whole web of ownership, profit and loss statements, bills of material, futures markets, taxation systems, shipping costs and so on. But to try to link this to arbitrage and HFT is a pure nonsense.
Then again, this sort of speculative (and flawed) thinking is just what economists do, right?
*re flocking: looks more like murmuration, but that's almost beside the point. I say "almost" because while you may be able to predict flocking behaviour pretty well, you've got practically zero chance of predicting behaviour in a murmuration. As with markets, there are too many free variables.