Bullhorns were created for time trial bikes back in the 80's to give a lower, more aero position.

Positioning drop bars: the tops should be parallel to the ground, and the top of the brake levers should carry this further so that you have a long, level area to rest your hands. This usually results in the ends of the drop bars pointing more towards the rear axle. You can also mount the levers a bit higher to suit, especially if the forward reach of the bars is a bit longer.

What's interesting is that drop bars were invented before the days of "ergonomics." To most beginners, it looks as though the natural position of your hands in drop bars should be in the drops. No! The natural hand position is on the top of the brake hoods. You only go into the drops if you're going hard and need to be aero. I spend less than 1% of my time in the drops. The downside of this assumption is that most people set drop bars too high. They set them so that they are comfortable in the drops. This is not correct; they should be set so you are comfortable on the tops of the brake hoods. This is why brake hoods today are designed so ergonomically. When you go into the drops, you are supposed to be a little uncomfortable! You'll get used to this, and the lower position will make pounding into the wind much easier.

You can always tell it's a beginner because they're riding in the drops at normal cruising speed. Experienced riders (well, experienced racers anyway) would be on the brake hoods in this situation.

Luis