I just don't really understand all this complaining..
"Nobody wants cables and external stuff around their places....."
What's the real difference from a drive to 4?
You most certainly would still buy some external drives to keep your stuff safe.
And if you didn't really know it: You can connect up to tens of external thunderbolt HDD (or SSD)-cases - just to one thunderbolt connection. What it means? If you like your place nice looking and clean, but together for example, 6 of Lacie's 20Tb Thunderbolt systems, but them in row of three (and the other 3 on top of the others), connect them to each other with 0,5m thunderbolt cables, and then with like 5 meters cable to your computer, and voíla, you can see just one cable going around, and you have faster connections than sata3, and nicer looking than USB 3.0. Yes it's possible, and those 20tb drives costs like $2000-4000 each (and if you can afford the new Mac Pro, you can afford atleast one of those.)If you didn't read it yet - You can connect up to 6 different devices to one thunderbolt cable.
It's small, but more powerful than Mac mini. Exactly it's like a tower version of Mac mini - except - with Mac Pro's power. And when you think about it really hard, Everything made for Apple devices, works with them.
Lack of PCIe card slots? The ones who really needs them today, are maybe the ones, who doesn't have enough power to handle .r3d -files and the Pro Tools HD/HDX users. Well, that computer has enough power for the .r3d -files, and I'm pretty sure that the Pro Tools HD/HDX PCIe cards are coming to change to some thunderbolt stuff later this year. But and again, if you can really afford Pro Tools HD -, Red camera - or this Mac Pro, you can really afford to buy some thunderbolt PCIe closure. And always you can run with the HD Native system until they release something better and new. (You know, so many of them who needs raw power for editing and stuff uses the last year's or older iMacs? And most certainly this is more cooler and powerful.)
Then we come to the RAM. "Just 4 slots." Right. It's a Pro system, and even the Mac Pro before supported 16Gb RAM sticks, even thought Apple didn't sell them. That means, you might get up to 64Gb's of RAM, and it's enough, if the last Mac Pros have been enough for you. And now it's faster and with 2x bandwidth - I think you can work with it really well.
"No DVD/CD/Blu-ray -drive." If you work with them or your clients wants the stuff on them, you can easily afford an usb 3.0 blu-ray drive. It's just one cable, which you can easily tape to your desk that you can't see it. You can still burn the discs, even thought the drives ain't internal. How does the iMac users work? With external drives. And todays, it's better, faster and sometimes even cheaper to buy usb 3.0 Blu-ray drive for the new Mac Pro, than a Sata II drive for the older Mac Pro.
This is like, if you are really going to buy it, you most certainly have enough money to buy an external TB HDD system, you most certainly have enough money to buy external PCIe cases. And if you really need more graphic power, you really can afford some extra cash for external PCIe place.
You talk about the price too high, but if you can't afford it, buy something else. If you have no enough money for it or/and the externals, think really, do you need it - was it then external or internal, it still costs almost the same.