Or maybe the "tower workstation" market is going nowhere fast for Apple.
Bear in mind that, in the EU, they dropped the Mac Pro months ago for want of some minor tweaks to meet new EU regs that have been in the pipeline for years. That kinda suggests that Mac Pros haven't been selling hand over fist.
The good old days when Windows was a half-baked DOS shell that couldn't create files bigger than 2GB, and the PPC G5 could run rings around a Pentium are long gone. Plenty of pro software now supports the PC, and for every package that still runs better on Mac there's probably another package for which the Windows version is always more up to date. Apple are staying in the pro market out of inertia, rather than any unique selling point - but they must be continually losing customers to Windows/PC (and maybe even Linux in some areas like servers).
Its all well and good having a Mac Pro with PCIe slots into which you are free to plug... er, well, the handful of overpriced cards that actually support OS X.
The new Pro is clearly an attempt to do exactly what they've done in all other areas: stick their neck out and do something radically different that stands out from the crowd and challenges the perception of what customers want. Yes - its a risk, but the upside of that is that the more conservative PC market (who have more to lose) aren't going to rush to follow them.
Look at the pattern over the years:
- Completely switching CPU architectures twice - 68k => PPC => Intel Core - on each occasion the new machines were initially unremarkable, if not slower, until all the software had been updated.
- Dropping floppies (initially, making them optional on laptops)
- Dropping everything except USB (when, although most PCs had USB, it was rarely used).
- Making a phone with no keypad... - the horror!
- Dropping optical drives
- Going SSD-only for laptops
...there was always an uproar at the time but, by and large, they were on the money and people didn't look back. If it was left to the PC world we'd still have PS/2 connectors and on-board floppy controllers.