Serious Face
Pro
You were more than likely playing her wrong.
The hide and res tactic was only on specific maps and usually on defense - Anubis B.
Most good/top tier Mercy's like myself, boost dmg or are busy healing. The hiding to res thing wasn't really advised, especially in 2CP and Payload. It was common on Hanamura and Anubis B, those of course being known as pure cancer maps, had other problems to deal with. Also you'll still be hiding with the new Mercy, as hovering like a moron while getting targeted by every dps/turret in the game isn't going to be fun.
More battle Mercy's isn't smarter, its lazier and bad for team work. I don't want the healer focusing mostly on DPS...there's an entire bracket for dps, and many other toons in other brackets dps as well.
The part of her ultimate I'm not a fan of is that she flies around in the air for the duration instead of controlling when she stays in the air, which makes her vulnerable to fire. In addition, I think she should not have infinite ammo on her gun. There have also been videos of her still flying around while slept by Ana's dart (will get patched, I know). And I agree about the battle Mercy, you may get more players that focus on attacking instead of healing.