Is not like there wasn’t any thought put into ulting before Valkyrie, is just that there was no room for error when you have Rez instantly done with the press of a Q.
Well, actually, there used to be. Mass Rez without invincibility made it so you could punish a Mercy for holding onto Rez too long while waiting for her entire team to die. But then, Mercy could never survive a Rez because she’d be punished all the time.
Mercy couldn’t had instant rez without invincibility.
Then Blizzard tried to hotfix it (very lazily too) by making her invincible while Rezzing. That took away any sort of room for punishment and decreased the window of time a team had for getting Mercy killed before she pressed Q. Now Mercy always survived a Mass Rez and made Tempo Rez a thing. So now Rez couldnt be countered, and Mercy could use it as another get-out-of-jail-4-free card from any ultimate if there was a soul nearby.
Now the game couldn’t had instant Mass Rez with invincibility. That hotfix made us believe that if we could see souls, we could Rez. That is why it feels so bad to rez in current time: just because you can rez doesnt means you will get a rez.
You have no idea how many times in Plat a Mercy behaves like: “Mercy sees, Mercy do” when there is a soul in her sight, gets herself killed and blames the re-work for dying.