Interesting that the trend towards lighter gauge heat-treated steels in normal gauges (753, Prestige, etc.) came alongside the fashion for short wheelbase/short chainstay frames. Building frames with those tighter dimensions with .8/.5 or .9/.6 or 1.0/.7 gauge tubes might have resulted in harsh rides at all but the larger size frames, say, above 59cm c-c.
The option of thin-walled lighter-gauged normal diameter tubing which was still dent-resistant (a principal benefit of heat-treated pipes) made the tighter proportions more comfortable while also resuling in lighter weight frames (good for marketing!) that resisted denting.
I note that wise American frame makers like Brian Baylis and Richard Sachs et al have avoided short wheelbase/short chainstay designs. They also largely skipped tubing like 753. I can only assume they build their frames based on the primordial geometries of fit (because that's what counts most when you ride) not simple wall thickness/weight equations (a fool's game).
What happend with OS tubing is probably outside the CR definition of KOF frames. Who really needs OS tubing on a classic road bike, anyway?
There are many ways to save weight on a complete bike which do not compromise ride and durability the way light-gauged tubing may.
More important, a comfortable rider will pedal his machine longer and faster than an uncomfortable rider, never mind how light his steed may be. That's what ergonomics tells us, anyway.