Easy Multi-Editing of non-Instanced Lights
It should be possible to select a set of lights and make group setting changes on them. This will also speed up workflow speed substantially. In 3ds Max, unless the objects are already instances, this is not possible, and sometimes keeping the objects individual has its benefits, and going back and forth between instances/non-instances is tedious.
For ex. track or ceiling lights tend to be the same e.g. 6 lights mean 6 separate edits rather than one for 6 and given the lights are clones this should not be necessary. Perhaps doing these as 6 instances would take care of it but that means they always stay the same and there are times when you want to tweak a light or two when testing so being able to edit one or all lights stills is possibly needed. Copies give the most flexibility.
Light-centric exclusion in Arnold
The Arnold Include/Exclude functionality has many shortcomings, and it's not nearly as flexible as the old 3ds Max native Include/Exclude. But the fundamental issue with Arnold Include/Exclude is that it's object-centric, not light-centric. If we want a light to only shine on one object, then we have to add an Arnold Properties modifier to every *other* object in the scene. This is a workflow nightmare.
If Arnold lights had the same functionality as other lights, this would not be a problem. Lights should have the ability to include or exclude objects. Objects having the ability to include or exclude lights is not good enough for real production problems like simply trying to illuminate a character's eyes and nothing else.
Lighting Analysis Assistant and Light Meter integrated with Arnold
For lighting analysis, we need to use mental ray. But now NVIDIA terminated its development and Autodesk acquired Arnold as main renderer. Therefore, lighting analysis needs to be updated accordingly. Otherwise, it's useless features. Autodesk is now working wih V-ray to get the function up and running (link). I cannot understand with one of their Flagship product, why can't Autodesk make their own rendering engine and put it together as a nice user friendly package
Blur the horizon of the Arnold physical sky
It would be great if the horizon of the Arnold physical sky environment node could have a "blur" function as many other daylight systems of other renderer can do. Especially if you want to render the background visible, this would be a great corresponding feature in combination with the "turbidity" property of the sky light.
Add the possibility to shift the horizon of the Arnold physical sky
It would be great to have a simple possibility to shift the horizon of the Arnold physical sky environment node up and down.