To say "I will always love you to death be us part" is a very destructive thought pattern. I should remain in union with you if you beat me? If you emotionally abuse me? If I fall out of love with you? Love does not require a legally binding contract. Financially it cripples couples and imprisons them together in the name of "marriage", and is incompatible with the notion of human nature; we are allowed more than one friend in our lifetime, so why not a lover? Marriage does not empower, it takes choice away.
Some may say marriage gives people security, but then so is a place of imprisonment and detainment. If you feel safe in walls of iron bars then by all means get married, but I personally think people are happier when they are free; when they are not bound by vows they can't keep, when they are not bound by the whills of another partner, when they are not financially crippled by the vengefull force of an ex.
A world without marriage, is a world with less chaos.