In his new book; High Performance Cams and Valvetrains, Billy Godbold states Comp Cams has a room with something like 20,000 masters stashed away. Crane and Isky are probably the same. Many of those old profiles worked well for many people. The thing is that R&D has shown some new ideas or revelations that promote valvetrain stability. A lobe profile could unsettle the valve spring causing it to surge. Valve float or spring failure can result.
DV tells of a cam PAW sold that was something like a 4th or 5th "once removed" copy of another manufacturer's cam that had a "deviation" in it that caused spring surge.
