Makes no sense, Pro's dont need or want a built in display neither do many consumers. Same reasons apply for both. Ask yourself why ProMac isnt a all in one.
Personally, I think the iMac serves a good market. But, I think it's deployment should be more limited.
There are those that want an all-in-one. But, that does not include me.
I would find it ideal for a student, for a bedroom, a dorm room, or even the kitchen.
But, as a primary desktop, it falls short for me. I have two primary issues with the iMac:
1) I can't open the current model to blow the dust out without really getting into an involved process and likely voiding my warranty.
2) I've been through the iMac G5 systems. Two of them. And, they were always in the shop for something. When the screen died (happened once on each system), the entire machine was in the shop. When the computer died, I was without a monitor to use on a borrowed system. So, I was without the good parts while waiting for the bad parts to be repaired every time.
With a separate monitor, I can still use the monitor with a borrowed computer if the computer has to go in the shop.
With a separate monitor, I can just connect a different monitor if the monitor dies and has to be repaired under warranty (or if out of warranty just throw the monitor away without losing my computer).
While I really did like the reduced cable clutter of the iMac, I really disliked losing everything every time a single part failed. And, I actually found that the moment I plugged-in my external FireWire drives (to make-up for not being able to add a second internal drive) that I had cables on the desk (instead of behind it) to provide data and power connections. Then, my printer's USB cable had to connect, then the keyboard and mouse. And then the ethernet, modem, and so on.
By the time I was done, it really wasn't as cable free as it looked at first. The only difference, was that instead of having the cables go to a tower under the desk, I now had the cables on top of the desk all going to once place (the back of my iMac). So, the clutter was more obvious than it would have been under my desk.
Of course, I could go wireless. But, I refuse to use wireless. It's a security risk, it's yet one more thing to have to trouble-shoot every time something fails, it means batteries (which mean on-going expenses), it means stuffing more stuff in closets and running cables into closets to keep the wireless items out of sight. Basically, it's just as many wires, just moved to a closet is all.
In short, bring back the mid-range desktops without a monitor. I miss the old PowerMac line with a wider range of builds. I could get them at $1400 to $1500, and I could also get them with higher-end configurations.