Guys .. the nr 1 issue is column size, not thickness.
A 30 x 30 cm column is VASTLY more rigid than a 15 x 15 cm column.

Likewise, a 200 mm free length at end of column vs 400 mm is 8 x less rigid, not 2x.
It´s length power of 3.

Original bridgeports had about 30 cm columns, and they are very floppy.
A modern haas is about 40 cm, but lots of internal stiffeners, but only about 10 mm thick cast iron.
It´s decent.
A modern japanese machine is about double the mass, with bigger columns, and thicker skin.
It´s very good (expensive).