I think instead of "casual" it should be called "beginner" it is an introduction to the quests and proceeds normal it would not be as derogatory as some fine the term "easy" and would be used to explain that this mode is scaled down to teach the ins and out of said quests.

But to call it casual to me assumes that people who may consider themselves casual players arent up to snuff enough to handle normal settings which to many of us with dungeon scaling has become laughingly easy. Maybe its the choice of word with this mode but I just think a even easier version then normal that isnt solo should be introduced as beginner just like level 0 in a game proceeds level 1 at times.