"Commoditize your complement" means that cheap-to-provide yet valuable services will be offered for free, simply because it drives down the total cost of buying

"Commoditize your complement" means that cheap-to-provide yet valuable services will be offered for free, simply because it drives down the total cost of buying from their main profit center. Regardless of how valuable Amazon's open-source AWS-related tooling is to developers, it's still not in Amazon's interests to charge for the software.