The alternative is building a large machine containing vast empty space on the speculation that someone might fill it - leaving almost every unit significantly larger than necessary.
TB2 is fast enough that putting the storage outside the box makes sense. Makes upgrades easy: plug it in, rather than having to tear the box apart.
I totally agree. The new Mac Pro is plenty expandable, the expansion just happens on the outside.
I've had two Mac Pros so far. They're great, and I love the internal expansion... in theory. In practice, they never got any PCI cards beyond the graphics cards that came with them, and I used the hard drive bays more because I could than because I really needed it (e.g. keeping the old drive in the machine when upgrading storage and using it for secondary stuff).
About the only problem will be GPU upgrades a few years down the line. TB2 is not quite fast enough to make that a good option. But most Mac Pro owners don't upgrade that, and it's plenty good for storage and other PCI cards.
> Makes upgrades easy: plug it in, rather than having to tear the box apart.
In theory yes, in practice it comes with a hefty price tag. External thunderbolt disk arrays are quite expensive and something that would be unnecessary if the mac pro had some form of support for internal drives.
TB2 is fast enough that putting the storage outside the box makes sense. Makes upgrades easy: plug it in, rather than having to tear the box apart.