I was 15 when I first read S&S and I was completely swept away with both Marriane and Willoughby. It's only 15 years on that I can read the novel and appreciate Austen's use of satire with regard to Marriane, and it's in light of this I don't think we should judge her too harshly. Austen is perhaps warning her readers of the perils of romantic sensibilities being taken too far. It's one thing to be passionate and emotional, it's quite another to surrender yourself to your emotions completely without regard for anyone else.