Sorry but this is just not accurate. The computer was sold out/backordered well into mid-2014, and since then, of course this is anecdotal, but I spoke with a major LA-based reseller rep and he said it was the best selling mac pro ever.
The truth is that the "pros" on here complaining are far outnumbered by the actual people who are busy working with their mac pros, who don't have time to complain online. Vocal minority and confirmation bias. Anecdotal again but in my specific industry mac pros are used a lot on set and in post production facilities. Their small size and portability, quietness, and TB2 ports are favored in these types of environments.
It's not meant to play games. Or make VR. Or run synthetic benchmarks that you can brag about online. Get a PC for that.
It's also silly that you guys think Apple will go back in time and release an updated model with PCI-E slots and a bigger chassis. The whole point is to move away from internal expansion and do everything externally and with modularity. If that doesn't work for you, thats fine, just go get an HP z840 and stop clogging these forums with vitriol.