I have read a bit about Louisa May Alcott, and I think she was reacting against the idea that all girls will end up marrying, and that if they are good, they will end up wealthy. I think she wanted Jo to decide not to marry at all and to be an independent woman who deserved respect for her own qualities. But since everyone loves a good romance, she decided instead to make sure that Jo married someone who only had love going for him. If Jo had married Laurie it would have looked like wealth, youth and good looks were the only important things in life. Anyway, Laurie was just a boy, and not wise enough for Jo. Jo deserved better than Laurie, and I think she got it.