Whenever I think about how the Palmers and Middletons seem better suited to each others' spouses, I always think of Mrs. Jennings in S&S2 declaring (about Colonel Brandon) "He's bound to do for one of you."

Even though this line is not in the book, it seems that among this set there is a certain kind of an 'any man will do' type of attitude. We actually do see this played out on a number of occasions.

Mrs. Jennings had been 'remarkably quick' to discover Colonel Brandon being 'in love' with Marianne (even before he did, apparently), mainly because "he was rich and she was handsome". That was reason enough to match up any two people, however unwilling. Mrs. Jennings had been "anxious to see Colonel Brandon well married" ever since she had met him. There was even an attempt to match up Colonel Brandon with Charlotte Jennings.

"[Colonel Brandon] would have been very glad to have had me, if he could. Sir John and Lady Middleton wished it very much. But mama did not think the match good enough for me, otherwise Sir John would have mentioned it to the colonel, and we should have been married immediately."

"Did not Colonel Brandon know of Sir John's proposal to your mother before it was made? Had he never owned his affection to yourself?"

"Oh! no; but if mama had not objected to it, I dare say he would have liked it of all things. He had not seen me then above twice, for it was before I left school."

Despite what Charlotte tells Elinor, I don't think it was her mother who objected to the match, and I doubt if Colonel Brandon was trying to promote it himself.Colonel Brandon's personality is no better suited to Charlotte than Mr. Palmer's is.

Mrs. Jennings got a baronet (probably Sir John is a baronet)for her eldest daughter and a respectable young man who's apparently interested in politics for her youngest. Personalities and suitability didn't matter. Rich +handsome=a good match, and it doesn't much matter who's on which side of the equation. As Mrs. Jennings tells Mr. Palmer, "You have taken Charlotte off my hands, and cannot give her back again. So there I have the whip hand of you."