2004 8051 unit sales 1950
2004 8051 unit sales 1951
Bank issues aside, it's not that bad. It's just different. There's few instructions to learn, their self explanitory, and they work as advertised. PIC...
bad if you can get a macro buttembler to emulate a reasonable buttortment of instructions, but then you still get to work around the ram and eprom bank issues. That said, the 8051 is itself made fairly tedious by having only one dptr register and too few general purpose registers- but there are vendors who sell derivatives of the 8051 which improve the situation.
The big win with a PIC is the small form factor, cheap programmers and how cheap & easy it is to get parts and that it can source-sink 20ma or so on each pin- which makes it easy to plunk a cpu down in an otherwise simple circuit without adding drivers for all IO. OTOH the ram-eprom bank issues make it extremely difficult to manage large programs that take up most of ram & eprom and the shallow stack is always there waiting to cause problems.
Since the 8051 doesn't have the ram and eprom bank issues, its lots easier to manage big chunks of software. I think there are 8051-alikes that run up to 90mhz maybe more, far faster than any PIC I've come across. The 8051 onboard peripherals also tend to be a lot more user friendly than the PIC equivalents.