Some things are central examples of caring (caring about the homeless), and other things are noncentral examples of caring (caring about sleeping late, caring about leisure activities). Whether a speaker describes something as “you should care more about X” or “you should care less about Y” does communicate information—it depends partly on how central an example of caring he considers X and Y to be.
(It also depends on how broad X and Y are. If you want to tell someone “you should care less about the entire range of activities that includes everything except climate change”, you would probably describe it as “you should care more about climate change”. So it doesn’t follow that any “care more” can be reasonably phrased as a “care less”.)
Some things are central examples of caring (caring about the homeless), and other things are noncentral examples of caring (caring about sleeping late, caring about leisure activities). Whether a speaker describes something as “you should care more about X” or “you should care less about Y” does communicate information—it depends partly on how central an example of caring he considers X and Y to be.
(It also depends on how broad X and Y are. If you want to tell someone “you should care less about the entire range of activities that includes everything except climate change”, you would probably describe it as “you should care more about climate change”. So it doesn’t follow that any “care more” can be reasonably phrased as a “care less”.)