In this case the "product" is an automated system for paying royalties on the customer's creative output which Google is making money off the back of, and they haven't so much "dropped" it as changed the terms to compel the customer to agree to a distribution deal with YouTube.

If any other online hosting service (with substantial network or lock-in effects) changed their terms to give themselves rights to host and slap ads on any of your other public output there would be an outcry. Why is this one different?