So why aren’t any roshei yeshiva suggesting it?
Rav Miller suggested it. Other Litvish gedolim (especially in EY) are also in favor of it.
And this new proposal by the Litvishe gedolim for the boys to marry younger is a very big step in the direction I’m suggesting. I wouldn’t expect the chasanim to jump from age 23 to 19 overnight. 21 is a good first step.
APY: Not all Chasidishe tatti’s are gevirim. The non-gevirim manage it too.