Discriminating against things that are damaging or threatening helps over the short term. But over the long term, diversity leads to more adaptability. When things are going well, it can take a long time for a monoculture to find out that it has become vulnerable. Nature rewards adaptability... eventually.
"Nature" is not a singular entity to which one can ascribe emotions that happen in individual minds. I suspect the question is rooted in seeking an authority to (guide | blame for) your own emotions. I suggest that these individual judgements cannot be blamed on others; as you are the only person in your head, you're the only one to blame for the things happening there.
Evolution is probably on of the the most exclusionary phenomenons that can be thought of: a race without rules to survive (and reproduce) at the expense of all others. Nature is the by-product of evolution. I would say discriminatory.
