I don't actually know if the name needs to change. They changed the meaning behind the name long ago.
It's Disney California Adventure, no longer Disney's California Adventure.
It's a park of Adventure, Disney adventures, in California.
They may draw some inspiration from California for theming and such, but it's simply a Disney park, in California.
Man. That makes IOA seem even more like a masterpiece and Disney even further creatively bankrupt.
Islands of Adventure had the theme of adventures of a variety of properties. But most (all pre potter) were linked with nautical touches or facing/being an island or dealing with the water.
That being said. Rebranding a theme park name is not cheap and takes efforts. MGM to Hollywood Studios was a circumstance where that partnership was not relevant and would cause cost.