More flexibility and light control. Positioning is needed other than rotation.
We’re investigating making lighting more robust and exposing sIBL components for more control.
I use an application for 3D where placing an sIBL into an environment gives you 3 layers--lighting, background and reflection and control over location, layers (blend modes, etc), etc.
It's a very quick way to do a lighting setup--I usually use the lighting and reflection and turn off the background. Being able to control location, colorspace, and visibilty gives a lot of control over the lighting and you can add individuals lights as needed. Some of the sIBL come with backplates to use for compositing which is helpful if you want a background based on the lighting.