I actually liked the stronger pin stripes on Jaguar

Same! And I really liked the pill on the upper right of each window. Brings back that Mac OS feel.

I would best guess that each era of Mac OS design was heavily intertwined with display technology of the time. Pinstripes were for CRT raster. Brushed metal detail was for LCDs. “Sparkly” metal in Leopard was for higher res LCDs, and so on.