Sure .... but just as many of us who are "power users" willing to buy a high end machine aren't served ideally by the AIO form factor. I agree with the people who said they really never used expansion slots. I finally did on my 2008 Mac Pro but only for things like adding more USB 3.0 ports or for an audio card that wound up working better as an external Firewire version (less likely to pick up RF noise from the innards of the computer). If the slots weren't there - it wouldn't have been much of a deal breaker.
For me, it's more about the monitor configuration. I absolutely want to run multiple monitors. But you can't just neatly put between 2 and 4 displays on a mounting pole with the iMac. You're stuck trying to place a couple of displays on each side of it, where they look mismatched and their stands probably don't even let them sit exactly lined up with the iMac's own screen.
For me, it's more about the monitor configuration. I absolutely want to run multiple monitors. But you can't just neatly put between 2 and 4 displays on a mounting pole with the iMac. You're stuck trying to place a couple of displays on each side of it, where they look mismatched and their stands probably don't even let them sit exactly lined up with the iMac's own screen.
I’m tickled pink with my 8 Core/32GB/2TB SSD. I have 0 interest in slots as I find I never used them after my base configuration. I buy a machine at a spec that will last for 5-9 years.
I think there is a significant subset of pro users (people making $$$ off their machines) where the AIO is the perfect option.