Well you said it yourself; “anytime soon”, they never said Mercy’s kit is going to stay like this forever. What’s the harm in people saying they don’t like her?
Just because she feels fine to you doesn’t mean she feels fine to the majority of players, and just because she is ‘balanced’ to you doesn’t mean she’s balanced for the rest of us. I’m probably an above average Mercy player as of right now, I still hate her kit for reasons other than balance.
You seem more concerned about homogenizing everyone’s viewpoints to match your own rather than actually looking at these viewpoints and deconstructing them.