When the Darkhold first came out, people thought that it was going to be the situation Bear, mentions: That only ARC, CON and GLA would matter in the whole game forward. But Ifrit actually took all the classes that the Darkhold spurned and turned them into essentials. Same with Crafting and Gathering after 1.19. Materia made these classes a whole lot more popular. Even traditional necessary classes like CON will be altered significantly after the addition of jobs.

The game is growing and changing. No one should pick a few classes and get comfortable.