Higher end Smartphones have anyway always on displays. And the led needs screenspace - which should be maximized. That's why the notch on phones etc. was introduced.

Packaging design, cost, manufacturing complexity, reliability. LEDs require a breach on the case for the lens. This requires a couple components plus sealing plus testing. Affects IP seal rating.

Every physical breach of the case is a reliability, sealing, dust, water, etc issue. Those are the things they fail on phones, after screens and batteries.

The PCB now has LEDs on the edge thdr need special assembly care like the three buttons do.

Most people put protective cases on phones so edges aren't available.

The top is all screen. The bottom sees the desk/table.

Haptics, screen, vibration do so much the loss of the LEDs is pretty minimal.

Don't be surprised if the power and up/down buttons go away sometime soon.

Headphone jacks are a huge problem as is USB and speakers.