A lack of skills in low level dungeons isn't the primary reason you don't have 70s running leveling roulette. There is basically 0 incentive to queue for leveling roulette once you're 70 on your jobs except for really niche cases (3.0 relic, glamour, need tome crafting mats). If they fixed the incentive maybe people would queue, but until then it doesn't really matter what you do with the skills.