I'd be all for dungeons, regardless of level relative to the player, giving a set % of a level per run, ie, 20% of the current job level, so it would take 5 runs to go to the next one if you started at zero progress for that level. Add the once-daily roulette bonus to it and we'd have a recipe for greatness. I would very happily spam roulettes all day long even after getting the daily reward if this were the case.

I don't expect that this feature would cause current-content dungeons to die as people will still need/want the gear from it for progression and/or glamours. Hell, it might even make spamming a single dungeon easier. Who knows?