It would be so nice to be able to use all my abilities in low level dungeons. I absolutely hated doing low level roulette on my lancer because it kept putting me in sastasha where the best combo is just a "Heavy Thrust" followed by "Impulse Drive" spam with a few offensive cross class abilities thrown in. Since I leveled dragoon almost entirely on low level roulette, I never had a chance to practice any rotation other than the sastasha impulse spam.

It is also silly that while leveling my white mage, if I get tossed into a low level dungeon the tank will often be the one stone-skinning the group.

The abilites are all based on potency anyway, so just by scaling stats down they will do less. A high level player will do more damage than a low level player, but the stuff is so easy anyway that it doesn't really make a difference. It just allows level synched players to use their full rotations instead of building bad habits.