I wouldn't call the 6502 a RISC CPU.. It was clearly designed for humans to program, it has multiple and complex addressing modes and instructions to make it easier for us..
Sure it is a small instruction set compared to modern CPUs, but RISC is an idea, not a number.
I'd venture to say that RISC is designing with the goal of making very efficient instructions and allow very efficient compilers to be written for it.. It's the idea to have one faster way of doing something rather than multiple convenient ways, because the compiler don't care, and compiler vendors appreciate not having to chose between multiple almost similar instructions that may or may not be faster in some particular case if they don't have to.
Sure it is a small instruction set compared to modern CPUs, but RISC is an idea, not a number.
I'd venture to say that RISC is designing with the goal of making very efficient instructions and allow very efficient compilers to be written for it.. It's the idea to have one faster way of doing something rather than multiple convenient ways, because the compiler don't care, and compiler vendors appreciate not having to chose between multiple almost similar instructions that may or may not be faster in some particular case if they don't have to.