Mercy's skins are a bit fanservice-y imo. I would like to see something different for a change

Then… just accept it as a non canon depiction of her work attire…
I mean, Doomfist didn’t wear the fist with his suit that inspired the Formal skin.

It seems like you’re trying to maintain a sense of realism with skins that very rarely do so themselves. I’m just saying, liberties can be, and often are, taken with their design.