Do not quote the wrong age for the Muhammed (SAW) .He was "25" at that time!!!
1- When it comes to making a point, religion and sunnah is used as crutches.
Other sunnah is also to marry more than one women.
Will these women ever bring that 'sunnah' as example?
Also, we are talking about women here, and Khadija RA was a widow so she had been married before 40. She was not single or never been married. So that argument does not hold water at all.
Even more important, the prophet SAW did not tell or advised others to marry older women. It was his choice, he did it.
2- Not that older women are outcast, the only point I tried to raise is that if it is by their choice, older women lose the chance of otherwise good and long married life and be able to procreate with gaps multiple times.
For a good child raising point of view, if possible, it is better to have good gap between children and career women by choice cannot afford to have multiple kids (even two) back to back within couple of years.
3- Less time to procreate, they tend to rush for children. God forbid they want a boy or a girl, and they have only one kind of two children, then they have less time to try getting pregnant for a child with different gender.