Spell Staff rarity

I could be wrong but I'm assuming all the different Spell staves are rolling to drop as one item and then you have to hope it rolls the right type that you are using...

I've been noting that you get lucky if in maps you get just 1 of the type of spell staff you want, usually having to run multiple before one drops (lets say Ashen Staff as an example), meanwhile you can probably get multiple hammers and spears per map run...

This rarity compounding with the spell levels being locked to the level at which you found it is kinda putting casters that use the staff spell itself behind...

I'm also concerned about this becoming a more serious issue when more weapons get added to the drop pool, swords, daggers, flails, claws... Unless those are like the staves (still running with that assumption considered how rare they are) strictly all dropping as a melee weapons and then get rolled which one.