First, it is very likely that this new iMac design was green-lighted by Steve Jobs. To invoke "Steve would have never done this" probably doesn't line up with the timeline....
Speed bump how? The switch to Ivy Bridge involved a change to the mainboard to use the new USB 3.0, new GPUs, and other updates. The size and shape of the new 2012 motherboards is incompatible with the 2011 ones. If they stuck with Sandy Bridge components you'd heard the wail of "its ancient technology .... oh the agony.... fail ".
The fact is folks can still buy an iMac if they want one.
Go to google and search on "iMac buy" and click on the "Shopping tab". It even show you local stores with them in many cases. Amazon, Frys.com , Abt , Bhphoto , etc. all have them. Retailers like Best Buy etc. all have them.