I think getting married and having kids too early is extremely stupid for several reasons
1) college debt, morgage, car payments... you're looking at $100,000 in the whole from the get go getting married and starting a family just out of college.
2) you have to know yourself before you can pick someone right for you
3) people who are good marriage material don't just magically appear. in fact, it's probably preferable to date several people at once until you find someone you can get really close to
4) having a kid before you have enough money to raise them well is just irresponsible
5) similarly, you have to have proficient communication skills to properly raise a child. most people I've met with kids had horrible parenting skills and did not know how to communicate with their children at all, or else thought that they shouldn't have to. I don't like my parents very much, but I'm glad that they waited until they could at least be good role models before I came along (even if there communication skills are still terrible)
truth be told, I don't think the majority of people should even have kids at all. I'm not getting married until I'm at least 27 and have my finances lined out and in order. I would say a good general age for women to get married is 23-28 and men 26-40.