Darchei- that’s all fine and good so long as they are PREPARED to enter marriage earlier. I believe age is arbitrary. I got married at 20, and we’re doing just fine; I also know people who likewise got married at 20 and ended up divorced within months because they weren’t mature enough to handle the hard work that marriage entails. I also know people who married at 17-18 who are doing just fine, but I absolutely would not have been ready then, and probably would not have lasted long in a marriage at that time.
The same concept applies in the secular world- my secular college classmates expressed shock that I married so “young”, but that is because the typical American 20-year-old is nowhere near mature enough to be married, and it is because no one expects them to marry at that point. By us, 20 is a perfectly normal age at which to get married, and is even the expected age, hence, you find greater preparedness amongst frum 20-year-old women.
Unfortunately, less and less are truly ready. I don’t know why; maybe it’s coddling parents, seminary-induced idealism, infiltration of secular values into our communities, or something else entirely- take your pick. But too many women (and men) are marching to the chuppah woefully unprepared for life after sheva brachos. Instead of using arbitrary numbers to determine a person’s readiness for marriage, we should be looking at the individual and where they’re holding spiritually, emotionally, and responsibility-wise. If you want people to marry younger, you’ve got to do something to ensure (or at least encourage) all that to fall into place at a younger age.