It's a nerf without making it a pain in the ass to use. Using the old DM system would make it a fraction as useful as it is now, and make dva a more frustrating player to play. She was honestly not great at all pre-dm change.
What I don't totally get about the changes being discussed right now is with D.Va. I can get reducing the shield charge, but they're keeping the same recharge time, which makes me feel like it would be better to just put it back where it was when it just went on cooldown, but couldn't be cancelled....
I'd personally give it a longer range channel sort of ability, with her current movement. but a RATHER obvious beam, maybe green ro some such. like her current beams. So you can sure as fuck see what's happening and what she's doing on the other team, but as mercy you can angle yourself into a safe spot to do it
I mean she doesn't get to move as she resses, and it's a few seconds of just standing there waiting to be head shot -- sending her in as a suicide mission to res one person isn't a fair tradeoff, imo, and the cooldown is long enough that I think it's fair to let her live the res