I think people like the way the 6502 wires up to peripherals. Myself I think the Z80 is much better because it has enough registers and addressing modes that you can write compilers for it. I know they had C compilers for it in 1984 because I typed in a C program for CP/M from Byte magazine and got it to run on my 6809-based TRS-80 Color Computer. Programming languages for the 6502 were usually implemented with virtual machine techniques like

https://en.wikipedia.org/wiki/SWEET16

or the truly atrocious

https://en.wikipedia.org/wiki/UCSD_Pascal

which was one reason a generation of programmers hated PASCAL with a passion and declared you could pry BASIC from our cold dead hands.

Myself I'd want to hollow it out and put something based on

https://en.wikipedia.org/wiki/Zilog_eZ80

because it is way faster, has a bigger address space, and has wider registers so you can do pointer math over that bigger address space unlike this turkey

https://en.wikipedia.org/wiki/WDC_65C816

A lot of people enjoyed writing assembly for the 6502 back in the day though.