Please let me play multiple classes.

[Felis]

Why not? There is really no logical reasoning behind this that I can see. Are we trying to make the people who play less feel better about themselves or something? I pay for a game and I want to play it, is it really more complicated than that? When the level cap is raised all this gear that takes months of work to get will become useless, why gate it so early when there is a huge number of players who are already hitting this gate within 5-6 hrs a week?

Because the people who play 40 hours a week and get all gear for all jobs in the first month would start to complain that the next new gear come in 2 month and not next week.
Therefore the best is to do that even those who play 40 hours a week don't get all gears in the first month.

In old MMORPGs it was done with abysmal droprates.