I'm not going to argue about the point that MS is nowdays the best choice for an average cyclist, but there are at least two reasons why I wouldn't buy one FOR MYSELF:
1 MS intereferes with my POLAR HRM (it really does).
2 I'm a headlamp manufacturer, and in case I'd wish to have a bar light I'll just pick one of my lights and instead of headgear attach it to a bar clamp

Taking into account the fact that my clients are mostly XC-skiers, rogainers and orienteering sportsmen who train and compete using HRM, I doubt if anyone of them should use MS wihtout refashioning.