Most of what grows in this valley's yards came from somewhere else, and a great deal of it does very well. Lilac, apple, peony and most of the shade trees on any street here are introduced, and nobody sensible argues they should not be.
So "exotic" is not a warning. It is a prompt to ask one question: does this plant spread on its own?
A plant that thrives in this climate and also reproduces without help is not an ornamental — it is a future removal job, and frequently somebody else's. Seeds move on wind, water and birds, and the ditches and fence lines here are efficient at carrying them. A few introduced plants that were sold as ornamentals for decades are now the reason crews spend days on removal along the drainages.
Which is why anything introduced and heavily fruiting or seeding gets checked against the Colorado noxious weed list before it goes on a plan — List A, B or C. It takes a minute and it is not optional. Near a ditch, a fence line or open ground, that check matters more than anywhere else.
Everything that clears it is simply a plant, judged like any other on whether it suits the site.