You can play Nashi in rat decks or legends-matter decks, and its useful to cast value rats, those that enter the battlefield and make your opponents discard
This will also likely help keep the price of these cards down, and even if they do fetch a premium, it won't be a wholly unreasonable one
If it does, the effect that exiled it won't return it later
That alone is a huge plus, and then add in coming from one of the most popular anime franchises
Cyclopean Giant Diregraf Colossus Gangrenous Goliath Grixis Slavedriver Helldozer Lotleth Giant Morkrut Behemoth Necrosavant Nightfire Giant Rotting Giant Sludge Titan Vogar, Necropolis Tyrant Writhing Necromass Zombie Goliath
With split cards, instead of having to pay one cost and get a choice of effects, you have two cards combined into one, with two different costs