These are all valid points. Feeding zarya can be both intentional and unintentional and cannot be helped.
Zarya is the only hero in the game currently, that benefits off of absorbing damage. I think maybe if the incorporated another hero similar, but instead of receiving more damage, what if they did more healing, or gained more health. It just sounds absurd. And her bubbles do more then just absorb damage. They stop all CC (except direct contact) and it also cures you of Anti-heals from anas grenade. Not sure why it has that effect but it does.