Leveling multiple classes during MSQ?

[Jojoya]

A lot of people have the mindset "Must get to endgame ASAP, go go go skip all the cutscenes never do any optional content ever go go go go go"

... I wonder why this is the MMO they chose.

Because there are still fun things to do even if you don't have an appreciation for the story.

Or because they used to play one of the other MMOs where endgame was "the game" and leveling was just an obstacle in the way. They get brainwashed into thinking that every MMO is designed that way.