I don't know why women haven't figured out the desire for a younger wife is probably linked to the desire to marry a virgin. Men can't be certain of that with women in their 20s anymore.
This makes sense, but it correlates much more strongly with religion than age. The stats I've seen are that the average person loses their virginity at around 17. So sure, if you want to marry a secular woman with no faith, then you have to marry early - but such a woman won't
want to marry early anyway - whereas someone raised in traditional Catholicism, who has never married, is much more likely to be a virgin no matter their age.
These are all reasonable considerations - younger women are more likely to be virgins, they're are less likely to be career obsessed, they're more likely to give birth without complications, they're generally prettier - but all these things are only correlations. A traditional Catholic blessed with good looks will be more pure at 28 than a Novus Ordo Catholic at 18, nevermind atheists or protestants.
As for looks - I understand why 40 year old doctors often prefer 25 year old nurses to female doctors their own age, and there is a big difference in physical attractiveness there. But I don't understand how that extends to teenagers. Ladies in their early 20s are still at their peak in terms of beauty and fertility. This peak period may start at ~16 but it doesn't end then. Within that span, one's natural good (or bad) looks determine one's attractiveness much more than one's age.