Why wouldn't you date someone with kids?

I noticed this come up a couple of times in the topic about how much “history” is too much and I wanted to know the reasons.

Is it because you will have to deal with their ex and possible drama?
You don’t like kids?
You assume it will turn serious quicker than you hoped?

What are your reasons?

As a mother or 2 I still wouldn’t date a guy with kids. I know it’s unfair for me to say that because I’m a single mother as well. I’m just not comfortable with other people’s kids, I get freaked out; I know it’s pathetic.