Is it bad not to date someone with kids?

I like kids, but I want to start a family with someone who doesn't have kids for lots of reasons. I pretty much lose interest completely when I find out he has kids. I notice that lots of men seem to seek out childless women even though they have kids. I don't understand this. They are often not even honest in their profile. They make it look like they're single and then after a few chats, they admit they have kids. Then it's awkward breaking things off.