Why not give Sona a self affecting passive buff when she casts an ability?

I mean if the problem with Sona is her teamwide utility, then why not give her a passive that gives her(and only her) stats. Something like:

Q - Bonus AD and AP W - Bonus armor E - Bonus movement speed

Yeah it's the same as her pre-rework state EXCEPT it only affects her. So the enemy know that if she cast W, she is slightly tankier. If she's running away, she's squishy and if she casts Q, then her poke is higher but she can take damage.

Plus it could allow for some more progression. Q + W = slightly better heal W + E = initiating combo Q + E = Hit and run

And she'd still have her aura lights around her. Except it wouldn't be as pronounced when the active buff is over.