Those crystals actually hurt Flurry Heart to a certain extent, she acts unbothered especially in front of her subjects. Got to be the perfect model as the only born princess.
Cadence can reduce the growth and a bit of the pain albeit slow, but so can Novus, though his method is more of burning the crystals to remove its growth than lowering it which is faster but agonizing. Of course the former is lot more preferable.