Hi, Mike,
I agree with your points about leather, but
a) I don't think composites (or rubber) are a panacea
b) there is alot of "tradition" in most high end luxury goods, and sometimes, those traditions aren't "practical"
Many composites and coutchouc (rubber) are irritating or unconfortable because, among other reasons, they don't "absorb" moisture, and chage. These are some of the reasons cotton, wool, and other natural fibers are still so widely used even when micro-fiber, rayon, and other synthetics are so much cheaper now and have so many other "more practical" qualities.
Also, the traditional perception that leather and satin are "luxury" materials - I neither agree nor disagree with the reasons behind this, it just is.
Like real wood trim in luxury cars, 100 or 200 weight wool, and gold/platinum in sporting watches. From purely "practical" and "wear characteristics" standpoints, all sporting watches would be Ti or Steel or composite (oh, yeah, these metals are harder to finish/re-finish and after many years, tend to look tattered and dog eared...)
Again, not disagreeing, just presenting a differing point of view.
Cheers,
TM