I am not surprised either. Most of the Murano owner bought this car not for performance. And to be honest, SE version is pretty sporty anyway. Lowering - Murano would loose the look. At least in my opinion.
For most high riding vehicles, a performance strut/shock makes a larger difference than just a stiffer spring setup alone. While I like the firm compression of my SE strut/shocks, they do give a little bounce when coming out of sudden dips, which suggests their rebound isn't particularly quick. This was where the KYB AGX's (on my Maxima) excelled.