In the case of Brooks, I suspect the company has become aware of a "use it up and throw it away" among today's cyclists. They market their saddles to people who want a comfortable saddle today, not at some point in the future. Sure, there are those among us who complain the new Brooks saddles don't hold up the way the old ones did; but we seem to be a minority.
Whether they can get leather of the quality and quantity they used 50 years ago, I won't speculate.
As for Ideale, they have found a domestic source of leather tanned by the same method as they used 50 years ago. I am not sure I'm understanding what Katia said on CR: but I believe she meant to say they use leather from deceased dairy cows, rather than beef cattle; the latter may have a spongy quality. But as I say, I may have misunderstood her on this matter.
Brooks is trying to be a modern company marketing a traditional product to today's rider. They are trying to modernize and move with the times. Whether that is the new Ideale's goal, I can't say.
At any rate no one should mistake leather thickness for leather quality. Leather has many characteristics, some of which make for a good saddle, others not. Thickness is one of them; but hardly the only one.
An issue for the new Ideale (even brooks) is that they need the best characteristics for the top range saddles, in decades long gone, Ideale made a wide range of price point saddles, so "less than" hides still found use in saddles like the
#39 .
No economy of use today.