There’s a phrase: food not lawns. It’s usually used for promoting growing produce at home, but I think the concept needs a slight expansion: food or habitat, for people or animals. You mention decorative flowers, shrubs, and trees: there are many species of these that feed or shelter wildlife, so many in fact that it’s not in any way difficult to exclusively plant these over ones that don’t in most settings and climates.

In other words, there are plenty of “productive” uses of yard space other than food production for human consumption, of course. But I like this comic because I like the question posed (when expanded a bit): if we’re actively cultivating a plant, rather than leaving the space wild (where it could feed and shelter wildlife) and it’s not for us to eat, and wildlife can’t eat it or shelter in it either, then what are we doing?