I think finally that laptop principles applied to a desktop computer have gone too far.
I like the All-in-one aspect of the iMac for home, and some small business users, who don't upgrade often, and use the computer for more than 3 years. maybe they get their money's worth out of a built-in monitor.
Most business environments, the hardware needs to be swapped more often than the monitor does, and a very good monitor can last for two CPU upgrade cycles.
Mac Pro is ridiculously out of date. Mac Mini is nice, but not pro-grade. Maybe the new quad-core will start to edge into that, but probably still not dedicated graphics.
But now the iMac has gone too far to copy the MacBook Pro->Retina methodology. What is good for a laptop is not necessarily good for a desktop.
Weight isn't an issue. It sits on a surface. Thickness is not that big of an issue, either, ever since CRTs hit the dustbin of technological history.
Now it is just gratuitious thin-ness, at the expense of versatility and performance.
I would rather that the aluminum chin had gone away, and just been a screen, with a computer integrated into the back, with a thunderbolt jumper to a matching Cinema display, to offer two-matching-monitor usage.
I know Apple hates cabling, but fishing around behind a monitor, or disturbing the desk to turn the whole monitor, or iMac for ports, is TEDIOUS. and turning a 27 inch monitor is not a minimal space. It isn't as if they are in the base or something, and a USB, FW, or TB hub defeats the purpose of AIO.
The BIG thing is... they have now emphasized the hole in their desktop lineup that has been there for a VERY long time now.
Smaller and less overkill than the Mac Pro's old huge case, and often-unused redundancy (4 drive bays and 2 optical bays, and 4 PCI slots is a lot. Good for a few HIGH-power users, but most machines never see that much hardware expansion.
Larger and less minimalism than Mac Mini. Not laptop components.
Not integrated screen, and capable of dual or even triple external matching monitors, Apple or otherwise.
A Mini-tower.
Desktop/Server grade dual or quad core i7 processors, minimum, upgradeable to two physical processors with quad-core, or more.
Desktop/Server grade full-size DIMMS. 4 at least...not sure if 8 are really needed in a mini-tower, without upgrading to a larger full-size tower.
2 3.5" HDD bays, with hardware-RAID ready SATA controller.
1 2.5" HDD/SSD bay, also compatible with Apple's laptop SSD blades from the MacBook Pro Retina, with the SATA controller ready to implement "Fusion drive" between the SSD and HDDs.
1 optical drive bay, optionally blanked and unused, or used for additional HDD, or front-facing peripheral port array face-plate.
Dedicated PCI-E graphics card, possibly compatible with SLI bridging for upgrading to 2 discrete graphics cards in the aftermarket.
Replaceable internal power supply.
Full boat of back panel peripheral ports, USB3, 2x TB, a legacy FW800, and 2 ethernet ports.
That sort of mid-range machine, between the Mini and the Mac Pro, could do most of what people ask of the MacPro towers now, save for a very few that might use every inch of the big Mac Pro's internal capacity, and it would do more than the MacMini, and iMac can do, especially the new thin iMac.
This new thin iMac just emphasizes the hole in the lineup, under and including the Mac Pro tower.