I have in the past, but here's the Cliff Notes version:

- Fit, because of varying body types. To achieve the same torso angle (which is applicable to aero and power), two riders of the same height might need significantly different cockpit measurements/saddle positions, and often different frames. A rider with longer arms might do better with a smaller bike. Riding style has a lot to do with what will work for a rider, fit-wise (...and I'm not just talking about faster/slower when I say riding style).

- Aero, because a lower position almost always creates a smaller frontal area, which is typically more aerodynamic. Since wind drag is a key factor in overall resistance, aero has a great effect on efficiency. It should also be mentioned that for most riders/riding instances, the rider is the least aerodynamic part of the rider/bike combo.

- Power -not because the being lower necessarily gives the rider more power, but because a shallow torso angle gives the rider more leverage on the pedals, so that they can move more efficiently. Also, a rider makes/sustains more power if they are comfortable. When your torso is closer to horizontal, it helps to distribute road vibration more evenly across your contact points, rather than going mostly to your spine.

- Position. This mostly has to do with the aforementioned leverage, but a significant contribution is made to handling that is not often mentioned. This is because of weight distribution. As some have mentioned, greater weight on the front end helps the bike handle better. It's true, having a more neutral weight distribution does wonders for cornering, braking, and the riders confidence level.