a lot of times when using a HDRI as as skybox, I find myself adjusting the brightness so that I would get a well balanced lit scene. Most of the time this will however result in a burned out sky. To compensate for that and allow more flexibility also with regards of reflections, all serious render engines have different slots for 1. Light environment, 2. Reflection Environment, 3.Refraction Environment and 4. Background Environment. I do not consider no. 3 so important but the other are without doubt.
If this is not easy to implement short termed, then please give us at least a second slider to adjust a background / reflection multiplier.
This is a Basic feature, especially for real time environments.