Why level up bosses at T15?

So I just beat arbiter at level 92 and i decided to go into the next citadel with a max level boss because the game is essentially complete unless i grind up to T4 clears. Doryani one shots me and I loose 10% xp and the citadel key.

What is the point? Why would I not just down level my atlas for the easy citadel clear and guaranteed key? Actually, why would i even level up bosses at all? Their drops are trash and i just increase my chance of dying with no real reward and a huge xp/opportunity loss.

It is just garbage that I would increase boss difficulty with no benefit. Sure I can clear a juiced T15 boss with max atlas and no hit a fight but there is no reward and only loss. It is just dumb.

they'r not worth it - even if u can delete them in 2 seconds, just go for normal bosses

Yeah i think you are right. I might just downlevel my boss nodes on the atlas and never bother. Stupid design, increase difficulty with no tangible rewards.

Atlas skill points give some useful rewards like rarity or waystone drops. I don't see the exp gain or the added essence, shrine, strongbox to be useful. Otherwise I'm not sure if making the boss more difficult increases the drops. Stopped playing once I beat arbiter, but I believe you can make him drop more uniques on the atlas tree. Might be useful.