Bard Ult Thought

I'll say this up front, most people will probably argue that Bards ult would be too OP regardless of the numbers used in what I am thinking, I can understand that, but this is just a thought that maybe Riot could take into consideration somehow.

Bards ult is basically a forced AoE Zhonya's that can easily go terribly wrong if used at the wrong time, and most people seem to agree that using it in a teamfight that has both allies and enemies mixed together is usually not a great idea. So what if it had a tad bit more utility on it?

Just throwing an idea out... what if his ult healed his allies for a percent of missing health? Say healing for 8%/10%/12% (increasing at each new rank) of missing health for allies (maybe turrets... or maybe not). And for enemies hit it would damage them for 8%/10%/12% of their current health. Neutral jungle monsters and Baron/Dragon effect would remain the same.

The exact numbers and scaling I used is not necessarily what I feel like it should be, just an example. But it would make ulting an in-progress team fight more viable, and also just be helpful in other situations.

Thoughts? Reactions? But please, if you are against this, be decent mannered about it.