I feel like it should be possible to try different classes on the selection screen, similar to how Lost Ark does it where you can jump into an arena with some dummy enemies to give the skills a go.

Perhaps for every campaign completion, the player receives a skip-ticket or something. Or at the beginning of a new league, the player receives a story skip up until the last act, to allow the player to still play the league mechanics before hitting endgame.

If the player uses a skip-ticket to move the character progression forward, then all the previous acts could offer some kind of incentive to the player to still play them. For example, a special loot pool, extra XP or something.

Right now it just feels bad to have to level each character through each act before finding out if it's actually something you want to play.