For herbaceous plants, even a threefold increase in plant richness was unable to capture the diversity of Lepidoptera species and interactions supported by fewer keystone plants (Fig. 3).
While this may be true in their findings, It lens itself to overapplication similar to edge habitat and early succession habitat leading to increases in diversity. It unlikely depends on the specific questions asked in the study. Is an increase in caterpillar biomass really needed over diversity. You can have both. I'm my point above, I don't think any state in the US suffers from lack of edge habitat, not is there enough old growth to suggest suffering from a lack of successional habitat. Similarly, I can't see planting ANY red maples. If you have them within a mile you'll see seedlings every year. The biggest reason they're as prominent as they are is because of poor logging/replanting and the fact that they will grow in a sidewalk crack. If one is going to make an effort, I think it's always better to increase diversity, plant harder to grow or get started plants, and have both quantity and quality in mind while directing one's efforts.
