Why is Hymn Nocturnalist a sustained talent?

[HousePet]

The redesign made it a passive talent partly to reduce the number of buttons you ended up with on your hotbar.
Was it changed to give you the option to turn it off? If so, I guess that is fine, since it can drain 15 negative energy per turn. But if you don't like the drain, wouldn't you just not put points in it?
However as a side effect of the modified code, you now don't get the negative energy regeneration from the talent if you don't have the sustain active.

So either the negative energy regen bonus should not require the sustain active, the sustain could be modified to drain negative energy slower (perhaps less beams at lower energy levels), or people could harden up and it can be passive (You can still disable a Hymn to stop it firing).

[Elkan]

So you can turn it off when you do not want to be killing things.

For example, pacifist missions in the Infinite Dungeon. I want the moment speed buff from hymns so I can rush past enemies to the exit, but I do not want to be blasting everything to atoms as I go and failing the mission.