JA understood the importance of money, and IMO she knew that just as people who have annuities are bound to live forever, people who have just received legacies are suddenly free from worrying about money (at least temporarily) and therefore look younger and more relaxed. Also, she wrote that she was *agreeably* surprised to find Louisa Bridges still there (which she wouldn't say if she disliked the woman, IMO) and the word "wholesome" also makes me think that JA was not being ironic in a negative way, here.