They didn’t change Mercy’s GA going from OW1 to OW2 for giggles. It was because the SJ issue in OW1 was a bug in the coding, and while they confirmed that and agreed to let it stay in the game, they also said they were not comfortable leaving it as a bug in the code, because you can’t control that. There could be a lot of unforeseen complications because the scenario that caused the SJ to happen in the first place was a bug.
So going from OW1 to OW2 presented them with the opportunity to finally code it into the game properly, as they obviously were not going to intentionally port a code into their new engine. So they pretty much had to try to find a way to replicate -to some manageable degree- GA/SJ in OW2.
They didn’t change it for fun or to try to improve Mercy players lives or anything, it was because they had to code it into the game. They tried several iterations to get it as close as they could. So saying ‘revert it’ isn’t remotely a possible route here; it was a bug that was removed, and the effects of the bug were attempted to be replicated. They’re not going to try to bring a bug back into the game, even if they could. Trying to code around an existing bug when you don’t know how it would react or why would be just idiotic.