The thing with Aria is that it was supposed to be important due the requirement to farm Souls that are the core mechanic of the game. As far as I known it was supposed to be like that considering how items that are suggested for increase your soul drop focus exactly on the Luck stat,
It'd be nice to see the stat reworked somehow, though. I think the issue that springs to mind with a lot of these stat systems is that they tend to mostly be locked into genre conventions from early RPGs, so more action-oriented games like the Castlevania series can't really play into an obvious tweaking of values as much as something like a turn-based RPG might be able to. Still, it's always fun to see these kinds of systems get evolved in different ways.