Burst healing

So i know currently soraka is in a really good place looking at her winrate and playrate. Although after playing 100's of games with her, i feel as if the burst in the game is too high and she becomes a really annoying heal bot. For example, the enemy team usually targets the adc in team fights but the burst is so high that before you even have the chance to ULT the adc is dead.

imagine a scenario where the adc has full life and you know the enemy assasin/burst mage is going to initiate his combo on your adc anytime soon however at this time the adc has full life so you can't heal him but wait for them to initiate their combo. But in the next 0.3 sec the adc is dead and i Ult 0.2 sec late and this varies on which champ/s burst down your adc. Usually when i just spam all the buttons (R, solari active+ W + summoner heal) my adc usually does survive a burst but that is spamming without thinking and really not fun.

First of all soraka's ult heals for 50% more if the ally is below 40% health. Secondly, soraka should technically be using ult and summoner heal when her own health is down as that's her only method of healing herself fast (other than her Q which is over time healing). Third the solari provides a decent shield for 2.5sec but you should be using that together with the W so that whilst the shield is being used up you are also healing the adc with your W's but for that to work the adc has to lose some health before. The point is that the burst is so high that all the technicality is thrown out of the window and your left to spam buttons. I may just spam the W first and heal the adc when his life was full or etc. So what does happen is that your usually left to heal everyone in the team like a healing bot going right and left instead of supporting your adc during team fights. I do realize people are not happy with the high damage LOL has currently but i don't think there is a simple solution to that which riot will be implementing on anytime soon.

Simple solution What do you guys think if soraka did more healing for a higher health + mana cost? It's already ridiculously high (10%) but healing can be overpowering if it doesn't have drawbacks. It's also not hard to tweak unlike a full VGU rework etc.