I'm guessing it's a conflict between developers and management. Questions like "what protocol should we build our messaging system on top of" is an implementation detail decided on by the developers at the beginning of a product's lifespan. Stuff like handling encrypted messages gracefully is simply a developer doing their job thoroughly, not a directive from management to focus on the XMPP API. Then later in the product's life, when they want to build a platform and business integrations and sending money and all that other monetization stuff, restricting third party client access suddenly becomes important.
