Probably because of where they live RHC don't seem to be sensitive about carb icing - the same probably applies to the other piston hele makers. Anyone operating piston/carb heles in temperate climes has a different view. It is always difficult to make financial sense of anything to do with heles, but a mod to retrofit these sort of systems to these heles has to be a good idea.
One of the paradoxes of our safety regulation system is that it inhibits developments that would improve safety, because of the enormous cost of the process and the small market from which to recover the regulatory costs.