As someone working in the lighting and architecture field, I require IES (Illuminating Engineering Society file format) lighting support for importing, modifying and baking real light fixtures.
Pretty much any light fixture and lamp that you can buy comes with an IES file and a lumen value. If you use both of these along with the area of the luminous area, you should be able to reproduce the lighting of 90% of light fixtures available very accurately
Currently Unity dos not import IES lights from 3ds Max FBX exports, so everything has to be baked externally in 3ds Max. Unity also uses light "Intensity" with some unknown generic unit instead of proper "lumens" as the light unit.
Adding IES support and switching the lighting units to Lumens would allow architects to present their designs as "real" and based on real world units. It would also allow us to determine if the lighting is wrong, if we should use another fixture or lamp wattage instead. It would not make sense to show the client a bright office with a lot of lights on the wall and then when they build it, the office is dim and the wall is not lit. We must be able to use Unity to detect lighting problems in advance and make sure our designs are as beautiful as what the client will build in reality. Else it becomes a deceptive guess-working game to make the game look good rather than figuring out the real results of our design choices.
I don't expect live IES support. I am OK with only baked lighting for IES. Our building often have more than 2000-4000 lights, so having all the lights live in VR would not work.
The standard for IES lights is described in the following document
IES Viewer (free):