Only problem is..
Want a decent matte screen? Don't get an iMac
Want a uniform screen? Don't get an iMac
In the context of two screen set ups, how many folks need two matte, high color fidelity screens? If keep "color work" and menu bar on "external" screen and email/IM/reference manuals/etc. (i.e., not primary work task) on another screen then doesn't matter as much.
If trying to minimize system costs ( a single screen and single CPU package) then loose. iMac also isn't going to "1/2" the cost if packing 4 core and lots of RAM in it. The upper end iMac can trim off the folks who only really needed more cores and RAM.
It is a completely different story if want to get into "apples to oranges" where want to provide Mac Pro but with cheaper parts ( cut the power supply, dump ECC, cheapen the case , etc. )
Want to be able to replace your hard drive eventually since they all have a 100% failure rate? Don't get an iMac.
Eventually everything has a 100% failure rate.
Want a decent GPU? Don't get an iMac
Decent to run photoshop ?
Want to be able to add storage that is NOT limited by a usb2 or firewire bus? Don't get an iMac.
Disks are in the TB stage. Is there a good reason to keep your work project from 3 years ago live on your primary hard drive? It is one thing if most folks were going to access the files. It is quite another when more than a few folks have large numbers of files on their drive that haven't been accessed in years. Being capped in that context has little real impact. (other than having to do "spring cleaning" periodically. )
There is a gap between Mac Pro and iMac. However, it isn't as large as folks are making it out to be. Especially, in the areas that are close to the overlap in non-display hardware.
While there are folks who need higher I/O bandwidth, more flexibility, ability to store and secure more stuff inside a single cabinet, etc. , there were also folks who were buying Mac Pros not because it was the right fit, but because it was closest match (limited i/o, limited flexibility, etc. )
Even in terms of I/O. Not quite there yet but if added USB 3.0 and Lightpeak to an iMac there would fewer needs for PCI-e slots. The trendline is clear. No-slot boxes are going to be the mainstream even into the lower workstation space over the next couple of years. There are folks with legacy equipment and addicted to the familar form factor, but technically ... no reason why number of people covered by that solution won't get bigger.
The iMac's are certainly lacking in many areas that standard desktops cover with ease. Remember, the PC market is growing,
The Mac market (in terms of units) is growing. You're going to have really hard time convincing Apple their strategy is doomed as long as they are selling more Macs this year than they sold last year.
As the PC market matures the trend only grows that larger groups of people buy from the small group of profitable large vendors. Apple isn't #1, but are in the top #10 in general and in the top #5 in subsegments.
If people move from lower end Mac Pros to iMacs ..... both of those put profits into the same bank account.
Apple is only treating it like it's dying because it creates hype for their iGadgets.
They aren't treating it as dying, but as mature. The race for the biggest winner in the PC market is over. Been over for long time. Apple can sit and treadwater around 4-6% . As long as they can keep it a constant 4-6% year over year and pull profits from the market it is not a losing strategy.
It is a market that is maturing. Hype doesn't have as much of an impact anymore. Being regular and being around is sufficient.
Additionally, as long as just and many folks leave in a huff because of no minitower are replaced by folks who don't want a minitower .... again nothing particularly wrong with the strategy from Apple's perspective.