How is it that the strong and weak nuclear forces do not have an influence beyond the nucleus of the atom?
What if I ask you that why a positively charged object is attracted to a negatively charged plate ? There is no answer to this. This is a purely metaphysical question. Or what if I ask you, why is the gravitational force an inverse square force ? This is pure metaphysics. Nature is this way.
The nuclear forces don't act beyond the nucleus. They are short range forces. That's how nature is.