We use 16 bit program counter because a program that is 256 location long is so small only a hobby person will use it.
My first personal computer (8080) had a CP of 16 bits. (before "DOC", back in the CPM days) (printer, hard-drive, monitor, floppy, etc)
The 8088 (one of the first personal computer) address 1,000,000. That is so small that no one will use now.
The 80386, has a PC so small that they all have been thrown in the trash.
I am typing on a computer with only 4,000,000,000 of memory and the new programs will not run on it because the programs are too big.
Can you find a micro with a 8 bit program counter?