Seconding what they said. Gonna post my own reply to this just incase but if one of those threads ever comes around I'll probably repost a variation of it there too.
The biggest thing I would takeaway from all of is this is that the playerbase at times can be notoriously terrible at providing feedback in a concise, clear manner that is digestible for the people that need to see it.
Likewise Riot has a consistent problem of taking feedback and interpreting it in the wrong way or even just directly taking actions that contradict feedback but without any given explanation.
Stuff like balance is much more common to be discussed, but stuff like VO's rarely if ever get the time of day on here or across any social media and so changes that have happened over the past lets say 5 years feel like they fall on deaf ears.
We don't expect to hear everything that goes on in your internal meetings but it would be nice if every now and then someone went "Alright hey guys we hear you on the VO length stuff, we're taking in your feedback and will get back at some point in the future with our thoughts and changes".
Now for the topic at hand - Realistically most people aren't and weren't asking for "stories" in their VO. They just wanted a bunch of short voice lines that gave you the personality of the character, but a lot of them so it was fleshed out and varied. Obviously you have to make them good voicelines because otherwise you start to hate them.
Nobody was complaining that champions had too many lines. Nobody. The 3 main things people didn't like when it came to some new/redone VO was:
1. Single voice lines that are too long. Sort of solved by moving some of them to the "long move" audio trigger, but now and then there are just voicelines where you click and they break some of your timing rules.
Honestly as long as they stay in the Long Move category it's fine, but people watched the video of the Ashe VO update and falsely tried to inflate that as her entire VO being too long, which I think is where a lot of the negative feedback came from.
2. Too many voicelines that can be heard by other players. This might be the biggest one I think contributing to peoples annoyance with voicelines.
"Out loud" voicelines should be saved for important skills/interactions only.
Restrict it to ultimates, and vital abilities.
Gonna use my flair as example because it's something I'm used to:
Lux W and E voicelines are completely unnecessary to be heard by anyone but the Lux player. You know whats important for my allies to see? The animation of Lux herself, and the VFX her shield portrays. Nobody is listening out for the voiceline "we're in this together!". It doesn't provide any gameplay benefit.
Your enemies and allies don't need to hear Lux say "banish the shadows" and "shine bright" for the entirety of a 10-15 minute laning phase when you activate her E. People hate it. It's annoying, and again it's not like you can't see her E right there. The voiceline plays when the E explodes, so it's not providing any gameplay tools for counterplay or telling/showing you something you don't know.
This goes for her legendary and ultimate skins too. Too many repeated "out-loud" voicelines.
Technically you dont need to hear her voicelines on R, but Ultimate sort of go by a "rule of cool". It's satisfying and cool to hear the Demacian champions shout "Demacia!". It's cool to hear Renata say "kill them and suffer!" as a giant chemwave flood rushes at you.
Super Galaxy Rumble is notorious for this. "SUPER GALAXY COMEBACK BREAKER" and "SUPER GALACTIC TORPEDO" or whatever the f**k he says over and over and over for the entire game is obnoxious.
You get the idea. This applies to stuff like Ezreal saying too many "out-loud" voicelines, Morgana, Irelia's Q lines (nobody needs to hear Ru, Kai, Oni, yomama all the time).
The lines can exist, there's nothing inherently wrong with them, just make them play only for the person playing that champ.
3. Overall shortening of VO lines. Even accounting for removing overly-long lines, newer and rework champ VO's are too short overall and so you end up hearing the same things over and over and over.
Zoe has 27 minutes of VO. You could cut 1/3 off that from the skinspotlights video because of the delay before/after voicelines he used to have in older VO videos and you'd still be in a good place. Briar has a measly 8 minutes start to finish. There's a healthy middle ground between those, and the team definitely has gone too far on the "short" side of things.
Sorry thoughts are a bit all over the place because there's so much I want to address, but I'll try organise them better if there's ever a dedicated feedback thread made and posted. Those are just my main 3 points.