I think you have raised some excellent points & agree with most of your conclusions. It is obvious from the beginning that Mr B is very unhappy with the woman he selected for his wife & obtains most of his happiness in the union from his relationship with his two eldest daughters - the ones who are the least like Mrs B (Mary is like no one else in the family). It would be natural for him to think of the side of marriage that he seems to have missed the most. Mrs B wants financial security for her daughters and for herself; I think we can assume that at least Jane (and perhaps Lizzy as well) would provide for Mrs B if Mr B were to die first. However, when Darcy slights Lizzy, Mrs B writes him off as a prospective son-in-law due to what she sees as his disagreeable attitude to her daughter. Under those circumstances, his money doesn't seem to mean that much to her -- after all, she doesn't encourage Lizzy to try a different tactic to entice him.