So my first M3 was a comp E46 and thought about a convertible but my buddy talked me out of it. He mentioned how the rear looked different and not as clean. So bought it and loved my car but he would loan me his car from time to time. After driving his car with the top town, music playing and his exhuast sound with the 4.10 gears I was sold on a convertible! So after selling my E46 what did I buy a used E93!! Love the car even though I don't drive it very much. When I do drive it the top is always down unless company in the car dictates otherwise.
I guess the benefits of living in California is the weather is livable with the top down almost year round. I also have a C5 convertible as a commuter and the top stays down unless its raining or below high 40's. With heated seats, wind deflector and the heater its not bad at all. Like someone else mentioned it feels so good and a great drving experience to have the top down. Its kinda like those that ride a motorcylce feeling the openess to the weather conditions and ride. I think if i were a track guy which some guys do here I would buy a car for the track only. Sure you can use your car for the track but if you rely on it daily and you mess your car up then your jacked. Also how often people actually track their car if not often enough doesn't justify not getting a convertible because of the extra weight. If your in a racing circuit or competing then yes every advantage you need. Otherwise maybe bragging rights at the best. Everyone though has their own reasons as individuals. When I feel maybe things aren't fast enough I just jump on the sportsbike and take off at a light and watch all the cars in my rear view mirror.