ALICE: "Hey Bob, will you come hold this ladder for me while I climb up on the roof, make sure it doesn't fall over."
BOB: "OK"
Bob holds the ladder, Alice climbs up on the roof. Bob gets bored and leaves, and the ladder falls over.
ALICE (on cellphone to Bob): "Hey you jerk! You left me up here on the roof! Why didn't you stay?"
BOB: "It's not like you were paying me or anything. You should be grateful that I stayed for as long as I did."
Now, how should Alice react? There probably isn't any sort of legal remedy she can take against him (just as there's no legal remedy that people have against Google for taking away their free services). But you can bet she's angry, and she's going to think twice about turning to Bob again, and she's going to warn all her friends that Bob is not to be trusted.
That's the "issue", and that's what's going on here. All free services have the potential to become an important part of somebody's life, so that taking them away can leave them up on the roof without a ladder.