I'd say go one further, lock MSQ 30+ behind jobs only, and all dungeons past level 30 (and guildhests 30+) can only be queued for by jobs, and all raids and trials can only be queued for on jobs, and same for PvP. Also, all mobs above level 50 gain a wombo combo move that will 1-hit kill ANYONE on a class that they use instantly on a class upon aggro (no cast time, they're immune to stuns etc, 500 yalm range).

Not only that but if you're killed by this move 3 times in a week, your character gets instantly deleted. No undoing.