status effects DO trigger when you use the ranged attack of the staff.
it's just that one, they typically start off at very low level (like 10%) so you rarely even see the trigger happen, and two, even when it does trigger, it can still be resisted.
basically, if you really want an effect to be useful on a staff, it needs to trigger at least 20% of the time, preferably 30%.
really though, if you are playing your mage right, your staff is just a stat stick, and any status effects on it are just bonus.
I can think of only ONE time in the whole game where I actually needed to use my staff to kill something because it was immune to the elements I could cast as spells.
don't bother with staff combat unless you are using a mod that allows you to really buff them up a bit. right now, you can't even add tenebrium to them so they will always be very limited in damage output.
I'd love to see a mod that buffs up staffs a bit; you could play a monk-type character.