Those are only the legal marriage requirements though. Virtually any couple that wants to get married can do so. It's easy; maybe too easy. However, the other prerequisites are much more meaningful and have a bigger impact on how happy a couple will be. What these requirements all basically boil down to are compatibility.
But what about the concept of "opposites attract"? The truth is that it is more of a romantic notion than true reality. Study after study has shown that even if opposites do attract, they very rarely stay together. this is because there is too little common ground on which to build a relationship. While it can be appealing to meet somebody that is so different from you, the novelty soon wears off. That doesn't mean you should each be carbon copies of one another, far from from it. But you should have a few things in common. Of course, these are all things you should know before you even start thinking about getting married.
There are three main requirements for marriage. If you find that any of these are missing, that's okay. Just being aware of them gives you a chance to make them a part of your relationship or improve on them if needed.
Good Communication. You have to be able to talk to each other, not at each other. The secret to this is listening. That's much more than hearing what your spouse is saying, you also have to pay attention and try to really understand. If you are unable to communicate with one another, then your marriage is headed for trouble. The good news is that better communication techniques can always be learned. That being said, communication will only work if you meet the next prerequisite.
Respect. Everything derives from respect. You take each other seriously (in a good way) and are accepting of you each are. Don't talk down to each other. While you may each have different roles within the marriage, neither one of you is more important than the other.
Love. As the old saying goes, "Love conquers all". When you have love, you can live with the other things not being what they should be. However, there can be a problem when only one of you are in love. This puts things too far out of balance, and means it will be harder to work things out. But as long as the feelings of love are mutual, there are no other requirements of marriage that really matter.