She’s not a requirement, this coming from an Aura main.
She’s just very easy to carry a team with compared to most other medics. In that regard, Aura isn’t the problem, it’s the lack of major team support abilities on other mercs like sawbonez, phoenix and especially guardian.
Aura has been nerfed to hell recently. Self-sustain is no longer a valid strategy with her, and new players rarely seem to pick her for anything other than an easymode shotgun. Doing anything more to Aura would make her an impractical choice, the other medics are the ones who need attention imo