Why do people think that Apple has to open access to iMessage? They run the services that make it work and they don't have to coordinate with anyone to make changes to the protocol, services or front end. They could make it open, but that seems like something that is not in their best interest for the stated reasons and more. I get that it's a default application on iPhone, but users don't even have to login to iMessage/Facetime. And assuming that all users do, now Apple has the burden of ensuring the service for all of those users. The premium they charge for their devices helps to pay for this; allowing access for rivals increases their burden without them collecting any fees for doing so. Although there could be benefits to this, Apple hasn't seen a reason to allow it and it's annoying seeing everyone get upset with Apple for winning instead of simply trying to compete.