You mean the non-existing UI elements of the streaming part that are hidden if you have not signed up for the service? These non-existing UI elements drive people towards signing up? Or the UI elements that are there once you have signed up, that drive you towards actually using the service you have signed up for?You've obviously never designed anything like the Music app. Apps on a subscription model you lay out the UI/UX to drive subscriptions and be friendly to subscribers with little regard for non-subscribers (You don't want them anyway).
Have you actually realised that once you have signed up there are no additional subscriptions they could market to you?
This is like accusing car makers to make their cars attractive to drive, to get people to want to use the car. How dare somebody make a product a user actually wants to use. Tricking the customer into buying a product by making it attractive to use.
Why do you think have music download sales dropped over the last couple of years? More illegal downloads? No, they have dropped because people are switching to streaming services. Apple isn't pushing subscription, it's the customers pushing Apple to offer subscription by stopping to buy songs. If they convert current song buyers to subscribers and make more money, it is because those people like subscription services more than buying songs and are willing to pay overall more for it. If Apple hadn't offered it, they would have switched to a competitor. Maybe Apple is speeding up that process by offering a product that is more appealing to current song buyers than competing streaming services or merely by making it easy (and cheap) to try it out.