I mean, being limited to 192 GB of RAM means the Mac Pro can't be used for certain applications, such as scientific stuff that depends on huge data sets, or as a server. But… those are extremely niche applications for Macs these days.
People, focus: we're talking about ONE HUNDRED NINETY TWO GIGABYTES OF UNIFIED MEMORY. Seriously. Yes, the old Intel Mac Pro supported up to a staggering 1.5 TB, and some PC servers support even more, which means they can cater to those rare use cases. But for the vast majority of creative professionals, yes, the amount of memory the new Mac Pro supports is more than enough, and those six free PCIe slots (only one less than those found on the Macintosh IIfx) give it expansion capabilities we hadn't seen since since March 1998, with the Power Macintosh 9600's six PCI 2.0 slots.
Calling it an underwhelming upgrade, especially considering how they didn't nix the rack-mountable version, and how there seems to be plenty of double-height slots and power plugs in there (which, duh, means they intend to support external GPUs), AND a few internal SATA ports and single USB port for hardware authentication dongles, is completely misguided. Also, that thing actually has eight slots total, which also means that even if the built-in I/O pair aren't standard or upgradeable, at least they are modular and, thus, inherently user-replaceable if something goes wrong (due to like, say, an attack, with a USB-killer or something, or just due to normal wear-and-tear), much like in the Mac Studio but without having to cut through all that glue or voiding your warranty.
Yes, it's $6999, but for pros that really need it, there it is. It's a Mac Studio with PCIe slots and space for internal expansion, dongles, etc. It will probably be like a few hundred dollars more than a Mac Studio kitted out with an M2 Ultra so, if anything, it's that machine that no longer makes sense keeping in the line-up (the only reason it might survive being nixed is it may make for a great colocation/cluster machine for render farms, or something).
You really aren't seeing the big picture here, now, are you? 🤔