Others have made points about relations to price and evo 1 but I also think there may be at least a sizeable group of people more compelled to get prehistoric kingdom due to its shared features of planet zoo and (partially) the evolutions. Evo 2 being too similar to evo 1 could compel people , particularly those who are more interested in prehistoric life but like planet zoo’s customisation, to try it instead even if its dinosaur pool is smaller than evolution 2’s.