Retractable hard-tops tend to be very heavy. When ASC added it to the VR4 for Mitsubishi it added immense weight to the vehicle. Also one of the contributing factors to the higher weight of several Mercedes models, and the extreme spec weight differences on the various F360 flavors. For me, simply too much further compromise.
I prefer either the closed top coupe or a targa design like on the Zonda, which can include interchangable panels (solid, safety glass, etc...).
Personally I don't mind having to manually lug it away.. and for adding only 88lbs is an acceptable compromise in the case of the NSX by any measure.