Worth bearing in mind, that although at close of 1.0, jobs only added 5 abilities to the class, consider that the devs will have planned out character progression to level 99 (or whatever they've decided the game will eventually cap at).

If we get a +10 level cap raise every year or two, with another five abilities for each job, and three new jobs every year or two, that's a ton of new abilities and options coming in the future.

I imagine that classes will continue to be used twofold; as gateway to unlock one or more jobs and as a stronger solo option.

Personally, I would prefer the class specialization you've talked about to instead be a different job (eg from THM, both BLM and NEC), but that whole job progression thing is a discussion for elsewhere. I can see your point for wanting the base class to fulfil the role rather than adding more jobs, I just prefer the thought of more jobs.