Ask your friend to start playing now, so he can catch up and become a machinist when the expansion hits. If he doesn't like it because he can't do it right away, well, that's his problem. We still don't know how things are going to be when the time comes, since Yoshi-p is always modifiying stuff on the go, we're still almost 3 months away from the expansion. I've waited for like 2 years to become a DRK...
And the "No MMO did this before" argument is something that I completely ignore when people state that. If I ever mention it, it's under request or to use it as a counter-argument when mentioned. People critize things because either "Every MMO does it and sucks" or "No MMO does it and they should". What about letting them have their own politics?
The expansion is not only "3 new classes", it's a lot of content bundled together, which includes new classes or jobs... or whatever they call it. Lore-wise (Because this is a Final Fantasy game. It implies it's a story-driven MMO), it makes sense. Why would you be trained in a job that doesn't belong to your lands? You need to migrate there and the story will lead you through said path. You'll unlock plenty of stuff on the way.
/edit: Silly character limit. Remove that pls.
