Oh, dear. The conspiracy theories are out tonight.
So, I can't speak for Apple, but I've worked for one of the top 5 smartphone makers, and I've been part of the decision-process to bring in FM radio or not into a new series of devices.
The major reasons _not_ to enable the FM receiver hardware was:
1. The use-case is counter-intuitive. The user has to attach corded headphones (the shield is used as the antenna), which doesn't make the feature usable at any time. Sure, we had pretty cool antenna engineers, but the RF environment within the phone is already pretty darn crowded. Also, getting a signal with a wavelength as long as 100MHz into the phone (as in, past the casing) takes work.
2. Enabling the FM receiver also enables the FM _transmitter_ block. This means that we would have to do type-approval in _many_ more countries, as there's a special series to tests that has to be done for FM TX, and they're governed on a per-country basis.
3. There are regional differences in what FM frequencies you should be able to tune to, as well as the spacing between the channels. Meaning, we would have to detect their geolocation and look that up in a table. Sure, there's some homogony within the EU, but people do travel to other parts of the world.
4. There's little to no demand from the actual end-users.
If a carrier explicitly requests it, we'll enable it in their carrier-specific firmware, but otherwise, it's not worth the hassle.
At no point was "our online music store", "our carriers music store" or any other economic factor besides "are the end-user willing to pay for this?" considered.