Marrying money in Trollope

The underlying assumption that fuels all the plot elements in Trollope's Dr. Thorne, and maybe in his other Barchester novels as well, is that the near-fallen aristocracy of England has to "marry money." There are references throughout to the impoverished state of the Gresham family, though there's no evidence to show that they live in anything but high style - maybe not as extravagant as some of their wealthy peers but they don't seem exactly to be cutting corners much less living the way most of their servants and working-class neighbors (subjects?) must live. They are completely isolated from reality and have no idea what it means to be truly poor or even strapped. They could sell their lands and easily get by. That said, why must the younger generation "marry money" in a misguided attempt to enable the family to maintain the facade and sham of its aristocratic manner? As the male heir, Frank Gresham, notes, he could use his education (Cambridge, no less) to earn a position in the law and make a living, support a family - and what's wrong with that? But no, his family just can't come to terms w/ earning a living based on your knowledge, skills, and ability - and actually, just maybe, contributing something to society. In fact, they even have scorn, disdain, and mockery for those who have made their fortunes through business and trade - constant reminders of the tailor's son, the ointment of Lebanon, and the stone mason who became a railroad baron. I know Trollope stands at some distance from his characters, who do not in any event express his views - but really, why doesn't one of them speak up and recognize that this obsession with marrying money is a chimera - a foolish attempt to maintain status that is going or gone, and at the cost of the happiness and well-being of the next generation, the children? I assume as the novel continues to develop there will be more revelations regarding the hypocrisy of the characters - if Mary Thorne inherits the Stracherd (sp?) fortune, suddenly she will become a desirable mate, but will she still be interested - and will the money ruin her as well?