I just have this Fanon perception of Sona having a Draven-esque personality as a renown Demacian/Ionian performer of the highest caliber. Reading through her old lore fragments, we get no interactions with her, or word of her interacting with anyone outside of her Etwahl, the league Summoners, and her noble adoptive mother. She entered the League because she felt it was the best stage to practice her musical skills in battle.
And in my head, a performer of the highest caliber shines in the main role, giving a slow-starting performance that ramps into a crushing finale. The same way Sona goes from a sluggish early game, to a fully powered, terrifying force when building AP.
Truthfully, while nuking people does have a degree of fun to it, it's really Sona's W and E scaled up that usually make me go 'wow'. I don't think any other champion can hit a steady 540 MS without boots outside of probably AP Janna and a handful of outliers. Not to mention giving similar mobility to the team. Similarly, the sustain you provide (up to 300-400/W!) to your team usually means you can act riskier, or longer than teams typically would.
Maybe it's just me, but i'd much rather she were reworked into a better midlaner kit-wise, even at the expense of her support role, IF need be. Even though she's unlikely to change for a really long time, given Riot's silence about her.