Soraka needs a more complex identity ingame beyond "being the healer"
Right now no matter how you do it, you only can screw up: if Soraka is strong she is percieved as oppressive as she just negates your damage. If she is weak she just sits behind in lane and is thr most passive champion in the game, while still keeping her ADC in the game with her heals. And that also pisses people off form obvious reasons.
The problem here is the fixation on Soraka's healing powers. I think it was Meddler who said some seasons ago that dedicated healers might prove problematic for the game, and in some aspect he was surely right about this. So how do we fix this now?
The solution is pretty much simple: Rework Soraka into an utility mage who would be THEORETICALLY CAPABLE of going into a Solo-lane, while at the same time not being unhealthy there.
I think no one has ever really complained about playing against Nami, right? I got my Rank 6 with Nami top and that was one hell of a game, I tell ya ^^
Nami is a mage, but just happens to function better with teammates around her due to how her kit works. And that prevents her kit from becoming so problematic as Soraka's is right now.
The question is now: where do we start there thematically? And here I would point to the E. We do not really have a dedicated Silence-Mage in the game, do we? "But Riot hates silences! LB got hers removed, Talon got his removed, and Kassadin still makes that joke despite..." yeah yeah I know. But it's not like they hate silences: they hate the mechanic just on champions with enough burst and firepower to just murder you during the silence.
On a utility-focussed mage a silence shouldn't prove too problematic.
Also I'd love for Soraka to be less team dependant. As much as LoL is a team game I'd like to have the feeling that I personally can actually impact the game in a significant way, even when my team is now not exactly the smartest bunch around (to say it in a polite way). Yes your heals can be extremly powerful, but if your team has the intelligence of a potato and/or is on full tilt... well, not even the 1-2k extra hp are going to save them, and you as a support just sit there and know that no matter what you do, there is no way in hell you could do more to win this game.
Also, before the haters start coming: I do not say that Soraka has to STOP healing. She can keep on healing, but it shouldn't be the only thing she does...
her health bar would also regenerate very quickly alongside her mana.