IMO it'd be a super neat addition for more casual content for sure. Gives us something to feed all the excessive oGCDs into.
The only pain point for me is how it would potentially collide with the 2 minute meta's emphasis on stuffing every buff possible into the window coupled with SE's love of ensuring there's some kind of mechanic lined up right with said 2 minute window. On one side, we managed before with Blood for Blood, but on the other side, it could start being problematic if we get 'Top to 100% or Doom' style mechanics in these windows.