nowadays, in highly developed cities, matured ladies are usually already very successful in their careers and so they are very confident of themselves.
A relation cannot work well if both want to be in control and lord over the other. So the 21st century woman finds younger men easier to control and manipulate, also, such a relation further boosts their self-confidence and esteem.
I juz saw a TV segment on this. They have a slang term in the US for these ladies - cougars

google for cougar hunters

IMHO, when something goes out of nature, that thing is gonna be doomed. (in this case, im referring to mankind xD )