There are game design reasons when you don't just let everyone get all of everything. Making decisions about your character (or party in a single player game) is supposed to be one of the elements of challenge, fun, and creativity in an RPG. Over the years though, decisions have been gradually getting stripped from just about every MMO in existence. You see a lot more people creating nonsensical names for their avatars because they can just pay to change them later. You see people making hasty decisions about their appearance because they can pay to change it later. People feel compelled to get every item for every job because the game lets them even though they don't have to. Letting people have everything creates as many problems as it solves. In most single player RPGs you have to make a decision at every turn, a decision that affects the outcome of a battle, a decision that affects the story, and a decision that irrevocably changes your characters. But put those things in an online RPG and everyone will beg for it to be removed. Why is this? can people just not handle decision making?
bla bla bla bla bla. You don't need to be the best at all 22 jobs, but that also doesn't mean you can't actually use all 22 of them. Why not enjoy choosing a path for your character instead of resenting the fact that a decision needs to be made?
Hell, I chose to be a Galka. Then I chose to be a summoner. Back when the game was new, you can predict the crap I got for doing that. Now, nobody cares. I can do my job just as well as any other SMN, and I can assure you my merits are probably not the same as yours. I chose to "waste" my merits on certain WS. Suprise! I can still play as my SCH or DNC or DRK if I really want to.