There is painfully little on regular FM radio anymore in the US. It is becoming the new AM radio. HD FM is difficult to support with a tiny antenna, I would presume by the lack of support already.

Besides, most US carriers blocked the radio API in their phones, so many in the US did not even know it existed. From what I understand, FM radios are still prevalent in phones sold elsewhere in the world, like South America and Asia, where FM is still the dominant radio signal.

isn't that some kind of anti-competition?

I hope (1) FM radio receivers come back, (2) and phones implement a way to grab the waveform and modify it before it hits the speakers.

I can imagine useful public-safety capabilities that could be enabled via data over FM radio.

FM radio is an insanely low-power, low-tech way to do medium-range one-to-many wireless communications.

The rise of HD Radio (which I assume phones didn't support), streaming audio (Pandora, Spotify), and even radio apps like iHeartRadio made it obsolete?

Only if you live in an ideal world with unlimited data and high speed wireless connections everywhere.

In my experience the world is still less than ideal.

There is usually at least WiFi everywhere you would reasonably expect to get an FM radio signal. When not on WiFi, even with capped data you can stream some form of audio. Barring that, you can store quite a bit of music on a smartphone, and get news in text form. Not much need for a radio on your phone.

There are hardly any open wifis in Germany :(

Increase in the availability of internet on the go and also of storage size also helped things.

Sony still includes a FM radio. The Xperia Z5 has one. As said elsewhere in this thread, though, their phones are more prevalent elsewhere in the world, not in the U.S.

Although I have a Sony Xperia Z3 and Z3 Compact, neither was bought through my carrier. While the Z3 does require headphones for the radio's antenna, you can play the radio through the speaker.

For the same reasons we are still stuck with android phones with 32GB instead of 256GB, "cloud, cloud, stream, stream, consume, consume".

... but don't stock, share, publish, modify or really speak freely? (ok I'll go get my coffee ;-)

Probably because they'd need another antenna to support that, and in the age of thin devices, I don't think anyone wants to squeeze an antenna on for a feature very few people would use.

Typically the headphone cable was used as the FM antenna. That has it's own set of problems, but it doesn't make the device bigger.

Many chinese phones also had analog TV receiver.