Said that I think the number of users that ask for a specific feature is not always reflecting the actual importance of a feature, usually, professionals have limited time to do jobs, and if they don't find a specific feature on the software that they have they simply switch to a different software because asking for a feature is time-consuming and they might never be implemented, and if they do it would require a long time which is not compatible with professionals schedule. I also agree that it's not Rhino's fault that IES lights are not supported: Usually, IES lights are particularly important for professional works in the architecture field which are never done with internal cycles renderer in Rhino, usually professional rhino users install third parties plugins such as Vray to overcomes the deficiencies of Rhino internal renderer, which provides better rendering times, more personalization on materials, and more lights types, so in my opinion if ENSCAPE defines itself as a professional rendering tool for architecture it can't lack of all the tools that professionals already use for rendering, such as good rendering times, better materials, and good lights (and maybe better camera controls, such as horizontal and vertical shifting), otherwhise there would be no point to pay 500 extra € only to lose some level of realism and reduce render times. However, because of the lack of this particular feature and some others (such as the possibility to change texture or color to the object library), I'm still not able to switch to ENSCAPE. But I'm periodically checking on new features because I really would like to use it since it's fast and I already own Rhino.

IES on ENSCAPE for Rhino would be much appreciated, I never took the time to ask for the feature because I didn't choose ENSCAPE in the first place exactly for the lack of IES support.

Rhino to enscape