Casters get spells on both sides, and keep them separate.

Barring quicken (And then shenanigans, which are not used by my group), you can only cast one spell a round, and my group is incredibly low-optimization and thus frequently at level 9 makes that spell magic missile. And most of my group loathes both quicken and spellcasters (Our one player who plays almost exclusively rogues and wizards hates quicken and refuses to take it on account of it being 'worthless', and I see no particular reason to convince him otherwise).

With no shenanigans beyond typical sudden strike ones, a rogue/ninja can apply their full lots-d6 to each swing.

I do understand - in many other games, this would be a nonproblem. But rogues are generally the highest damage-dealers in most of our games, and rogue/ninja was a particularly potent offender.

Again - I'm aware this isn't a typical problem for most people. ^_^