I think it is important to distinguish between diving a sidemount configuration and sidemounting. Most people will dive a sidemount configuration for many of the reasons mentioned (ie medical issues,it looks cool etc etc),but it is important when choosing to do a sidemount dive which involves small/tight cave,that the fundementals are learned-how to get unstuck,how to communicate to your buddy,gear removal etc. I've seen many people who have purchased an off the shelf sidemount rig and declared they are ready to do a sidemount dive,but the questions that need to be asked next is how.