i have the rain/wind deflectors on mine and i absolutely love them, and they serve a purpose for more than just rain.
In california we have alot of nights that range between 68-75 degrees so it doesnt quite warrant the ac being on, but it can still get kind of stuffy in the cockpit. And say i have the company of a female in the car, they dont always like it when the window is down and the wind is blowing their hair everywhere. Also, when the windows are down at 70mph, its quite loud. What i do on those beautiful nights that are so frequent here in socal is crack all four of my windows just to the bottom of the deflector and then i prop the sunroof open as well. This creates a very nice circulation of air that circumvents using the ac and is still quiet enough to have a conversation. It doesnt blow everything around in the car, just a gentle breeze. That is my favorite part of owning them, but I can agree that they are not the most visually appealing, but they are quite subtle and i have gotten used to them.
i can see how they would benefit smokers as well, but most of us who smoke choose not to smoke in our cars
but if you do decide that you do not like them and want them removed the plastic itself has a solid strip of adhesive that sticks to the weather stripping on the door. Also there are several tabs on the deflectors that are tucked under the channel gasket (or atleast i think thats what its called). You can just pull down on it and remove the tabs and then tuck it back into place. (or you can just watch this video and do it in reverse)
https://www.youtube.com/watch?v=X-LsU8DOXHE