Citadel bosses don't feel fair or fluid

yes, but this gets to another level when you try pinacle bosses, 1 arbiter attempt is worth 3-4 div atm, i killed him 3 times alrdy but with a broken build, this is not how it should be, these bosses should be more accessible. I can't risk my 3-4 div investment and die to a random 1 shot i'm not aware of coz i had no way to learn the fight.
Citadels should be more frequent, or there should be some sort of progression toward them, like "do n maps and citadel pops".
Pinnacle bosses should let us use all the portals, there could be no loot if u die, but that would be just fine, at least u know u can learn the fight after you died.