And in the next paragraph the article explains why: “There are tons of things NASA could use the new plutonium for, but there’s nothing on the books,” says Cas

And in the next paragraph the article explains why: “There are tons of things NASA could use the new plutonium for, but there’s nothing on the books,” says Casey Dreier, director of advocacy at the Planetary Society. “Why is that? Because NASA isn’t sure when or if it will have the plutonium it needs!” I don't think the argument is that NASA would be doing more if it had more RTGs, but rather that without more RTGs there will be new limits on the types of things it can do (no large rovers like MSL or outer solar system missions like Voyager/Cassini/New Horizons).