1) They did a cost analysis and it was alright, I can't imagine high-end servers with dual GPUs being much cheaper or much more expensive myself.
2) This isn't the 90s where Apple was at risk of folding and going away.
3) They actually don't other than phones. Go back to all their Pro desktop lines starting with the PowerMacs. The previous MacPro case lasted quite long and came from the PowerMac G5.
The previous form factor (silver tower) lived from August 2006 to December 2013. If we see that kind of longevity out of the black cylinder form factor, I'd be thrilled (although preferably with more internal updates). However, there's nothing stopping us from adapting our design to whatever new models come out.
We have current rack designs for Mac Minis and Mac Pros now, and we can add a third if the need arises.
> 2) This isn't the 90s where Apple was at risk of folding and going away.
No, but they are seriously unpredictable. Just ask anybody that built expensive workflows around Final Cut only to find out the new version wasn't backwards compatible with project files.
1) Massive premium for compute
2) They're at the mercy of Apple, a single completely unpredictable vendor.
3) Apple changes it's form-factors to the latest "design" way to frequently
4) Apple sucks to manage in mass