What's the reason (or reasons) new jobs aren't added to the initial roster?

[Bacent]

Yes, all classes have skills that they get at the proper levels from Level 1+, they don't have access to weapons and such from the same levels, not counting glamour weapons that are added. As well as them having to add additional class quests/lore to those lower levels as well.

I do wish classes would start at somewhat lower levels, but that's just so people aren't given a high level class they don't know how to play in the slightest.