In the case of Miss Taylor, she probably was not on the market in the same way. She simply met someone - and he was older.

I find it hard to believe that older men who have fully grown children, would ALWAYS want a wife who was under 25. But certainly many men are swayed by youthful beauty.

WARNING: Discussion below is a little morbid

As for Anne, I think she was getting older and likelihood of meeting someone was getting smaller. Afterall she had already met most or all of the eligable men in her area. She even recieved an offer from one.

BUt then again, a man who is already married could always loose his wife. So at some point Anne may pick up in the second round. And she may be more desirable to a man who actually cares about how his children will be treated in his second marriage.

If someone kind and domestic like John Knightley were to loose his wife, (after mourning her properly) he would certainly want a second wife who was able and willing to love a Bella, Henry, John, George, Emma and little Harriet... :) I could see Anne's steady mind and kindness attracting such a man.