That was more to do with the other support heroes being stronger not because Valkyrie is a stronger Ultimate than Mass Resurrect (they are about the same in overall power but Mass Rez occurred over a 2.25 second window while Valkyrie is spread over 6 stat changes and a duration of 15 seconds). Reworking the Resurrection Ultimate can resolve its issues such as this way:
Upon her rework her Resurrect range went up from 15 meters to 220 meters not including GA that alone makes it no wonder it that Rez became such an issue with that kind of range.
If the past issues with Mass Rez are addressed then those complaints can go away. LoS on Mass Rez is the most straight forward prevention of Rezzing through walls; Cast time may make it a suicide run to 5-man Rez, but that’s how it should be (big risk for big reward); increasing the Ultimate charge prevents it from coming up to much.
With a “Mini Valkyrie” on “E” that ability can balance out a harder to use, and less available Mass Rez.
She is viable due to her basics which didn’t change and because the other supports are weaker now (except for Moira and Zen).
Valkyrie is fight changer only if teammates make use of it; it’s not Mercy’s game changer that is put to the team to make true.
That is where the fixes to make Rez easier to counter fix the pressure to hide because if the team goes down then going for a 5-man Rez becomes much more likely to fail. Add that the Resurrection Ultimate can benefit living teammates and then there less reason to encourage “hiding” be teammates.
It OK for Resurrection Ultimate to be less likely to be pulled off because “Mini Valkyrie” on “E” fills void between the Core Kit and the Ultimate.
More like QoL change there which I would see no reason to remove.