I’m usually not into games that “start at max level” either, but to me, going through the boring parts of ARR was worth it to get to the amazing expansions. I wouldn’t even say ARR is bad. It’s pretty standard MMO content for the most part. It’s just that the expansions are so good that ARR looks bad by comparison.

As for leveling classes, you’re free to switch classes pretty much whenever you want. No need to make another character to play another class. You mainly just play lower level content to level other classes but it goes much faster since you don’t have to replay the story.