[Daisuke]

It seems more like minor inconvenience at best and there's a few ways to play around that.
Head into a crazy dungeon around your level when you're in the 20's and you'll start shooting up in levels very fast.

It's also why you shouldn't ditch your normal mage spells right off the bat. For almost every promo, you don't immediately start getting into it without a few a levels first. VAs can't do their insane backstabs without some points, BKs aren't as tanky, Kensei won't have their tons of buffs, Verglas won't be doing insane rapid kicks, etc. It's not really counterproductive, it's more like "You just got this class but you need to train for a bit longer using the skills you've already learned before you can fully utilize it" which makes a good amount of sense. It's like, you got to level 20 just fine playing as a mage, why kill your FP with a spell you haven't fully learned yet when the base class equivalent does more damage with less than half the FP cost.