Exercise, road riding (didnt like drop bars/brifters at all), and just plain fun!
My sirrus is a decently quick bike (the Allez I had smoked it, but it was not so comfy), that is comfortable and a joy to ride. I will likely never go back to drop bars, but I do want to add bar ends because I miss that "riding on the hoods" feeling, its more comfortable on long rides. Probably because its a more natural hand position. I also like v-brakes for stopping power, road calipers were scary at best if I needed to come to a quick stop. Of course, my Sirrus is nothing more than a endurance road bike with a flat bar, v-brakes and more of mountain bike gearing...