No it isn't the same, because when the original iMac didn't include a floppy drive, it did include another removable medium type - the optical drive.
You are fixated on a particular drive implementation technology rather than functionality. Those aren't necessarily the same. If can boot off the Internet, USB , Firewire, and Thunderbolt there is practically no loss in functionality.
You will need something outside of the Mac to boot. Whether that is a disk, internet connection, or external drive isn't a huge difference.
When the new iMac won't boot off the internal system, what are you supposed to boot off of? Does the new iMac come with OSX Mountain Lion preinstalled on an enclosed USB thumb drive?
Why is Apple doing the work or not an issue of functionality? If you want a USB thumb drive; make one. There is a Apple utility that will do it for you to whatever kind of USB , Firewire, SATA , etc drive you want to use.
For example, if you have a external HDD using for a Time machine drive then before initial usage as a target. Create a small partition and create a "rescue system image there". Make the rest of the disk a Time Machine target. That way if your internal drive completely fails you have a
FULL backup recovery system. In a rescue, plug in the HDD and boot off of it.
If want to split that work over two devices ( e.g., a TM target and USB Flash drive) that is fine too. Note that if you have a major internal failure it is far more critical that you have a back-up rather than some rescue disk with none of your data on it. That is missing the forest for a single tree.
The default if totally unprepared and Apple is suppose to solve all your problems for you is to boot off the internet. That isn't what they'd recommend, but is the minimalist work by user solution.