Yes, teens should wait until the age of eighteen to be in committed relationships. At ages younger than this, a teen is not yet a legal adult and cannot committ to the poing of marriage anyway. On top of that, at younger ages, teens are still having valuable new life experiences that a committed relationship may not allow for.
What if the teen wants to start experiencing what it is like to be in a relationships. It shouldn't be restricted because teens have their personal life and personal responsibilities too. They should be aloud to date maybe at the age of 13 and up or maybe junior high and up, but no less than that.
Teens should not have a designated wait limit or requirement to engage in a committed relationship. They are essentially their own individual, and sincere feelings can arise at any age. However, the responsibility doesn't rest solely on the couple; parents are extremely necessary in guidance for their children. I feel an approach from this perspective would yield exceedingly positive results.