Apparently the original story had the AI use the network of human brains as a giant neural network.

As the story goes, the movie executives thought this would be too difficult for most people to understand, so they switched it out and used the thermodynamically unviable power source motive instead.

I wish The Matrix had humans in virtual reality cages because the AI had a mandate to keep them alive and well, and this was simply the most efficient mechanism for doing this. This would have made the resistance far more ambiguous as they would actually be fighting for freedom but against the well-being of humanity.