Bearing Wall Seismic Force System 65' Height Restriction

[padgett01]

I have noticed that building codes before approx. 1999 allow a maximum building height of 160' for a bearing wall with light frame shear walls as the seismic-force-resisting-system for seismic design category D or worse. But then in the 2000 & 2003 IBC, ASCE 7-05, etc, the height restriction has been reduced to 65'. In most cases, we have the structural capability with our light frame (cold-formed steel) buildings to design greater than 65'.
Does anyone know why the big decrease from 160' to 65'? Thanks.