Not really because some plants tend to grow better in some climates than others. And we don't know just how many different plants exist out there. Just because we've already got something that works doesn't mean we can't stop trying or looking for others. Different tastes aren't a bad thing and some may have different or better nutritional qualities.
You realize that the process and genetic changes wrought by domestication have only begun to be understood very recently, that most domestication has taken hundreds of years, and that this is an evolving process for every species humanity has interest in, right?
As in, domestication is an ongoing process, and is unlikely to ever end.
