The only jobs that cares about Truesight is NIN and gathering classes.
If NIN are restricted from freely exploring in the same way as other jobs in a few specific areas, I don't really care. Gathering jobs are the same way, so long as those Truesight mobs aren't located directly by gathering points.
Stealth is so crappily implemented in this game, that even if Truesight mobs exist, like half the playerbase will never even realize it.
As others have mentioned, the very structure of this game pretty much eliminates most of the things on your list. Non-targetable is fine, because engaging in battle is swift and smooth. Magic-proof and physical-proof won't happen without easy workarounds, due to Yoshi P's insistance on job equality. Level caps are already in place, and handled smoothly with no gear requirements.
As for "unfinished jobs" PUP was never unfinished. The playerbase was simply dissatisfied with it. They wanted a solid DPS job, when it was designed to be a versatile support job, one that could tank, heal, DPS, buff, debuff, etc, in a reduced capacity compared to specialized jobs. Just as with RDM, the original "jack of all trades, master of none", it was neglected at first for that reason, but from the very start it fulfilled everything it was designed to do.
The new jobs here will be "finished", as well but whether or not they are acceptable to the playerbase remains to be seen. AST is the job I see being in the most danger, not MCN, due to its "dual role". It stands a good chance of being overpowered if it's fully competent both as a healer and a shielder, or underpowered if it trades off its strengths in both by being half-assed in both. The fact that its "mode" is locked during combat may save it from this problem; we'll see.
