Weaseling. It's called http://www.imperial-library.info/dogate/es_weaseling.shtml. Just because they give you some weasels doesn't mean you need to make a fur coat out of it.
Yeah, but there's good weaseling and there's bad weaseling.
No horses in Vvardenfell because they're a Dunmer delicacy and the local plant life gives them a fatal tummy ache? Creative and interesting; thus, good weaseling.
No dragons in Morrowind because the Cliff Racers dominated the food source common to both and, thus, pushed them out? Funny, humourous explanation (because of the annoyance and abundance of Cliff Racers in-game), and thus good weaseling.
The Khajiit province is called "Elsewhere" because it's named for an ancient proverb stating that "perfect society is always elsewhere?" Again, creative and interesting, and another example of good weaseling.
No Levitation in Cyrodiil because the Levitation Act of 421 outlaws it's use? Lame, boring, and unimaginative; thus, BAD weaseling.
My point is, if you're going to weasel your way out of a design decision or technical issue, put some creativity and effort into it.