There was a time where Mercy’s healing was buffed to 60hp for that reason.
Quite simply, sustained healing is cute, but it’s not enough to give Mercy players the freedom of doing more with their time outside of trying to keep team mates alive at those numbers. Even Animetic herself made complaints about it in the Geoff appreciation thread.
Even now, the issue with her kit, and Valkyrie, is that it is often too easy to have teammates die right in front of you, simply due to the amount of damage output heroes do now. In short, it’s not enough.
55hp would help with that lack, and I think a burst heal would be beneficial as well. Something that’s been discussed for years now has been a burst heal on her reload when she holds her staff. It doesn’t have to be a lot more, but something that allows her to better compete with the other main healers is something I see no problem adding to the game.
It’s time to make Mercy more impactful, engaging, and rewarding to play. I believe some sort of improvements to either her healing, her rez, or a new ability to widen her skill expression would be very warmly welcomed. Those that feel that #MercyIsFine is completely entitled to do so. But the amount of healing she does now, simply isn’t doing it for me. 
~Sincerely Yours xoxo,
a Lover of True, Fair, and Fun Balance.
xavvypls 