Plugging the audio jack seems to be Apple closing a loophole. It's not at all different from soldering RAM on motherboards to close the after-market RAM upgrade loophole and force customers to decide at purchase time how they'll use the computer in the future. Either they'll by too-low spec'd machine and have to upgrade sooner, or buy high spec'd and pay more upfront. Either way Apple wins. Their phones don't have card slots but my $50 LG phone does, so it's not a question of capability. When you can add 32GB of storage for $15, that money doesn't go to Apple.
The truly bothersome thing is how in denial people are about Apple's true intentions, or maybe it's simply that they own Apple stock. Apple's a public company, this is profit motivated pure and simple. Whether this move will also coincide with the interests of the customer remains to be seen.
(edit for typos and clarification)