When generating a 1 biome world under custom options, I have noted that no land animals will spawn in any of the mesa biomes.
I would expect animals to at least spawn in the mesa river biomes or mesa plateaus were there is grass - but there are none.
This is a major issue due to lack of cows, which makes it impossible to collect leather ... a vital component in books - which are needed for the construction of bookcases, enchanting tables and enchanting books .

I have also noted that no villages will spawn. I have walked over 14,000 blocks in survival, and flown around for literally hours in creative looking for a village with no luck.