I can't imagine the market of people needings 64gb RAM being significant enough to warrant its own product category.
The only way to offer this would be the f1 racing / supercar comparison made in a different article's comments on HN today. I think the new Mac Pro was an attempt at that and apparently failed.
But they should at least offer the option of 64GB RAM. Or 32GB as a minimum.
Basic specs are going to convince a lot more people than a mm or two of thinness. 16GB means a lot of work literally can't be done on that machine.
As for the Mac Pro - Apple made the usual mistake of building a form-over-function machine.
Mac Pro users actually need a tower with PCI slots, so that it's possible to swap in specialised hardware for DSP, graphics, machine learning, and so on. The only way to do this on the Black Bin Pro is to buy a PCI expansion cage that costs more than some of the Mac Pro models do.
The Mac Pro format would have been brilliant as a new Mac Mini, but it doesn't fit the needs of a significant number of pro users at all.
In the race towards ultimate and unnecessary thinness, the elimination of sockets for RAM and SSD dictate separate SKUs for every configuration they want to sell.