Indeed, When enemies are made, the areas they inhabit need to be fair in size so that they can be fought without "cheap" damage.
When Globox inflated, he flew, so there really wasn't much animation required there, as opposed to the Scaleman, which if the GBA version of R3 is anything to go by, would have had a lot more when "inflated."
Or maybe the concept just did not work in 3D, it happens to some gameplay aspects.
I hope that one day Ubi take a page from Insomniac and show off unreleased concept in a "Museum."
EDIT: I just realised R3 HD is meant to be released tomorrow, so here's hoping for a good first remake of the title...