I have three kids and a chocoholic husband. I really don't think my attendees would be so excited about making childcare arrangements, getting dressed up and driving to my house for 12 cookies either. The only time I would suggest one dozen is if you were doing an office cookie exchange and the cookies were going to be eaten only by the attendees. Six dozen is only one batch of a large yield recipe, or two batches of a smaller one. That's why I suggest people can bring 3 dozen of 2 types of cookies, if the recipe doesn't yield enough.
Many people do.
I iced my gingerbreads this year and they got the other cookies a bit sticky. This is kind of hard but we deal with it. They get eaten so fast in my house that the effort would be for nothing. But, if you don't have a family that will devour them you might want to separate the cookies and you can even freeze them to be eaten at a later date. This helps sets the mood.