In addition, you will be creating even more of an elitist shidduch scene. The “best” girls (yichus and money etc) will still get dates at 18 and 19. So now, getting married younger will be a real status thing.
I am glad that you put the word “best” in quotes, because it really is off-putting to think that anyone is judged as superior because they have money and/or yichus. That is a BIG mistake that many people make when looking for shidduchim for their children. Fortunes come and go (look at our economy today), and the fact that someone has a famous relative says virtully nothing about the person. If someone would have looked into R’ Akiva’s yichus, he would have had a heck of a bad time trying to get married. Oh wait – his shver DIDN’T want him for a son-in-law!His wife was disinherited for marrying him. The best boys and girls are the ones who show their emesdigkeit, middos tovos, and general ahavas Torah and chessed. And that should be present at ANY age.