I'm glad to see some positive support for kids in this thread.
The way I see it, if a restaurant does not want kids, then like Victoria and Alberts, ban them. Otherwise, it should be okay to bring them within reason. If your kids can handle eating out, if the parents make reservations at times when kids will do better and leave later times for adults. We figure, eat early, the kids are less tired, and it leaves the later times for adults.
That said, I've often seen teenagers act worse in restaurants than my 4 year old and I've seen adults acting in ways I would remove my kids from the restaurant for. So, its not just being a kid, its about manners and unfortunately, bad ones exist in folks much older.
I'll never forget a time when we were at breakfast in a hotel years ago, my oldest was 6, our other, at that time...have since added 2 more.....was 2. We had taken our seats , restaurant was busy, college football saturday, and a group of 6 people came into the restaurant. Instead of showing a bit of patience and waiting for a hostess, after about 30 seconds, they begin walking through the restaurant looking for one. My six year old watches them, and then looks at me and say...'dad can you believe it?" I answered 'whats wrong?' She replied, "dad, isnt' that rude? Shouldn't they just wait?" SO, the SIX YEAR old could recognize bad manners that the 60 year old had.
One trick we use, and this is almost every restaurant, we order everything at once, bang. None of this drink orders first, and then order. The reality is, we have kids, lets get things moving.