The Mac Pro was well enough received by some, at the time. It really excels if you need beefy AMD GPUs (from a few years ago) and want something compact and quiet and good looking on your desk. The problem is that while it has pretty good performance in general, there are crucial bottlenecks for a number of different potential customers which make some other product a better fit.

For folks like software developers or anyone else who is bottlenecked by single-threaded CPU performance, the Mac Pro is no faster than a machine like an iMac, and not necessarily even much faster than a current laptop.

For folks like photo/graphics/video pros who care about the best large high-resolution display, previous-gen Thunderbolt connectors/protocols and external display hardware weren’t quite ready until the past year. Apple could hack around the problems with the iMac because everything was internal, but the problems hadn’t quite been solved for a desktop tower.

For folks needing beefy GPU performance, the market is segregated between those needing workstation class GPUs and ECC memory, etc., many of whom are running CUDA software that will only run on nvidia chips (oops), and those who want to play video games or similar, and would rather cut costs with consumer-grade hardware.

For folks worried about future-proofing a big purchase, there was a lot of uncertainty about ongoing product support and upgradeability.

And of course for anyone trying to cut costs, there are a variety of cheaper Windows PC towers optimized to particular use cases.

Etc.

Ultimately, for many customers (say, university computer labs, software developers, photographers, graphic designers, even pro audio and video people), an iMac makes a better desktop machine than the current form of the Mac Pro, whereas for the folks who need absolute max performance, it makes more sense to run their work on some server cluster or something. Pro creative software that used to run primarily on desktop workstations doesn’t necessarily need them anymore in the same way. Video game players who make up much of the PC tower market are happy to stick with Windows.

It’s not that easy to find a cohesive market of folks who really need a super-expandable mid-to-high-end Mac desktop tower, and sell a specific bundle of features to them.

If they release a new Mac Pro within the next year or so, with the same concept/chassis as the first one but upgraded internals, it might become a reasonable fit for some of those customers, or they might have been chased away by now, it’s hard to say.

This bit from the OP also rings true:

> In this case, Apple’s timing appears to have been bad. There’s no way to know for sure, but it seems like Apple decided to dance to its own rhythm, skip an Intel chip generation, and then wait for the good stuff, only to get bitten by slippage in Intel’s schedule. If that’s what happened, it’s hard to blame it on Intel. After all, it was Apple’s gamble.

I think if there had been a couple of additional Mac Pro hardware updates since the original release people would be substantially less pessimistic about it now.