I agree that Valkyrie shouldn’t be discarded. I’m not one of the Mercy players that dislike it, and I think it’s a really good ult. In fact, I like it much more than I ever liked mass res. I don’t want a revert. I think res is inherently too destabilizing and difficult to evaluate, and I want a stable solution.
I see what you’re saying about the distinctiveness of Mercy with res, but I’m not a fan for two reasons. The first is that it doesn’t seem to be working. Maybe the 55 hps compromise you’re proposing would help and maybe it wouldn’t. I really do think there’s a threshold here, and I don’t trust Blizzard to take the time and find it.
The second (and more important to me) is a play style argument. No other character in the game has an ability that’s so disliked by its player base, to the point where they’re campaigning to make it go away and would happily trade it for anything else. If the ability carries with it the price of invalidating the part of the kit that the players do like, that’s a problem.
What makes Mercy fun is her play style of constantly darting around, evading the enemy, predicting the battle, and working hard to keep everyone alive with a medium healing beam. You’re playing a trickster character that manages to evade its predators and save the day. It only works though when the healing manages to keep people alive. Res can be Okay when you pull it off, but it can also be a chore. It stops her flow, and it feels counter intuitive with respect to the rest of her kit. It also cuts up her kit too much, putting too much emphasis on a thing that can only happen once every 30 seconds.
Mercy players flock to Mercy because of her healing and mobility. These are the two principles that Blizzard has stated as the core of her identity, and I really agree with them on that regard. I think she should be designed around them, and not around a clunky long cool down mechanic.
I’m assuming that you play Ana. As a point of curiosity, would you be willing for Ana’s grenade to be replaced by res? Personally, I wouldn’t.