For us it was to do with numbers. I am from a very large extended family and we had a rather small budget when it comes to weddings. The only children we had were relatives and all of our friends were understanding of that, because of the way we explained the reasons why we couldn't have friend's kids there. We only had about 30 friends and all the rest were family. We had 120 people at the reception. Kids were welcome at the ceremony, as we didn't need a number limit for the ceremony.