King of the Oathbreakers offers a different flavor of spirits than the usual UW fare
While the rarity of the Traveling Chocobo's several variants and exclusive prints significantly helps their desirability, the Traveling Chocobo's real power comes from how incredibly capable the new card is for landfall decks
At home in small numbers atop the curve of an aggro deck, in large numbers in a midrange or control deck, Glorybringer is so powerful, I can imagine it inspiring decks to be red just to play it
In any non-Commander format where Wishing and similar effects are legal, this is instantly the best Wish option you could run in most builds
If thats the case, and this is their island, why have they chosen to hide away and stash their Inkcaster
Future sets could print more towns, making this a more viable option, but as of now, this commander's second and third abilities aren't as relevant to most builds