I think the whole discussion misses one of the core use cases: CBx files may contain single images instead of a whole page. This case makes it possible to view the comic on devices that have a screen which is too small to display the whole page.
So if Illustrator supports exporting to CBx, that might mean exporting not as a page but as single images - or not. And even if Illustrator supports this, there is still the question whether The Giant creates single images and combines them later or not.
Personally I'd love to be able to read OOTS on my Kindle (even if it is grayscale only) or eventually on a smartphone (once I get one - I just spent a bit of money on a certain Kickstarter project )