I agree that when we're cultivating food a degree of garden hygiene has to
be maintained and the undesirable plants, native or not, will be weeded out.
When, however, we take on an ecosystem restoration project other factors
than yield for human consumption come into play. I like Mogli's line from
a, "Jungle Book," movie that points out, "Were you going to eat it? Was it
going to eat you? Then why kill it?"