A standard, more powerful part is usually much cheaper than having to do more customization, and these CPUs are so cheap that making it cheaper simply doesn't matter anymore.
For projects made in small quantities, as soon as you need a touch display, throwing an Android phone at the problem is often the right solution, even if you just need something extremely trivial. Sure, I could do it with an 8-bit microcontroller and physical buttons, but by the time I've designed a custom board for it, the time I spent was worth more than the phone.
It's still funny though. It's got more horsepower than an SMP RISC box from the early 90s that would have powered a top 100 website. And probably could have controlled a room full of coffee makers.
A standard, more powerful part is usually much cheaper than having to do more customization, and these CPUs are so cheap that making it cheaper simply doesn't matter anymore.
For projects made in small quantities, as soon as you need a touch display, throwing an Android phone at the problem is often the right solution, even if you just need something extremely trivial. Sure, I could do it with an 8-bit microcontroller and physical buttons, but by the time I've designed a custom board for it, the time I spent was worth more than the phone.