There are two kinds of "haze". One is the Rayleigh scattering, scattering of light off the air molecules, that's the one responsible for the blue sky. If you lower the scattering values, you will also change the sky color. The other is Mie scattering off the water vapor, that one can be lowered to make a dry air, but it's not visible much except low on the ground and looking towards the sun.
These values are physically correct, so if you feel they are making too much haze, there's probably a different problem you are seeing. For example, in the morning/evening the sun rays have to travel a long way through a denser air layers, and consequently they produce more haze as the light scatters more. With the sun over your head you'll see a clearer picture, but that's just because it's realistic that way.
Another thing that may cause a feeling of too much haze are the missing urban & civilization patterns on the ground. With everything mostly green it feels as if it was more blurred.
