Lifeweavers in my games consistently have the highest healing. That's not his problem. What is, is that he's a boring healbot that doesn't have any offensive utility. He needs a partial rework at the very least. The petal pad is the dumbest ability in the entire game.
TBF there are players who
want to healbot and support their allies so they can pop off. Mercy's a popular character even though none of her main tools interact with enemies.
(I realize Mercy has the damage boost, but from a "game feeling" perspective there isn't any difference between pocketing your allies with a yellow beam and pocketing your allies with a blue beam.)
Also I actually think the Petal Platform is really fun, lol.
It's a relationship there, the only reason he has the highest healing is because he's a healbot by design. His max healing per second is way lower than something like Ana.
He also can't miss, doesn't have to spend any time aiming, rarely has reload downtime, and can even arc his shots around barriers. It's true that being a healbot by design boosts his healing up further, but his healing shot is really, really good. Theoretical numbers don't tell the full story in Overwatch.
FWIW, I think Lifeweaver's actually good in his niche (defensive healbot) and is liable to be quite strong when he gets buffs this patch. I played a game with a Lifeweaver yesterday and he carried us through the first fight on the point by keeping people alive in situations they had
no right to be alive in. The brawl went on for a while, but it ended with everyone on our team alive.